Compositions and methods for the treatment of anorectal disorders

ABSTRACT

Compositions and methods for the treatment of anorectal disorders are provided in which certain combinations of NO donors, PDE inhibitors, superoxide (O 2   − ) scavengers, β-adrenergic agonists, cAMP-dependent protein kinase activators, α 1 -adrenergic antagonists, L-type Ca 2+  channel blockers, estrogens, ATP-sensitive K +  channel activators and smooth muscle relaxants are used.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. 119(e) of U.S. PatentApplication No. 60/222,267, filed Jul. 31, 2000. This application alsois a Continuation-In-Part and claims priority to U.S. patent applicationSer. No. 09/460,306, filed Dec. 13, 1999; U.S. patent application Ser.No. 09/595,390 filed on Jun. 14, 2000; and U.S. patent application Ser.No. 09/769,621 filed Jan. 23, 2001 which each claim priority from U.S.Provisional Application No. 60/112,325, filed Dec. 14, 1998; U.S.Provisional Application No. 60/139,916, filed Jun. 17, 1999 and U.S.Provisional Application No. 60/155,318, filed Sep. 21, 1999. Thedisclosure of each of the above priority documents is incorporatedherein by reference in its entirety.

STATEMENT AS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY SPONSOREDRESEARCH OR DEVELOPMENT

This invention was made with government support under Grant Number 1 R43DK 56563-01 awarded by the National Institutes of Health, NationalInstitute of Diabetes and Digestive and Kidney Diseases. The Governmenthas rights in certain aspects of the invention.

REFERENCE TO A “SEQUENCE LISTING,” A TABLE, OR A COMPUTER PROGRAMLISTING APPENDIX SUBMITTED ON A COMPACT DISK

Not Applicable

BACKGROUND OF THE INVENTION

This invention is directed to compositions and methods for treatinganorectal disorders such as anal fissures, anal ulcer, hemorrhoidaldiseases and levator spasm by administering to an appropriate anal area(for example, the internal anal canal) of a subject in need of suchtreatment an agent or combination of agents which relaxes the internalanal sphincter muscle. More specifically, this invention describescompositions and methods for treating anorectal disorders with agentswhich induce an increase in cyclic nucleotides in the anal sphinctermuscle or which mimic the actions of cyclic nucleotides or reduceintracellular calcium concentrations in the affected anal sphinctermuscle tissue, thereby reducing anal sphincter hypertonicity and/orspasm in patients afflicted with such disorders.

In general, anal fissure (fissure-in-ano), anal ulcer, hemorrhoidaldiseases, and levator spasm (proctalgia fugax) are relatively commonbenign conditions of the anorectal area which affect subjects, includinghumans, of all ages, races, and sexes. While hemorrhoids and analfissures do not garner the attention given to life threatening diseases,they are responsible for considerable suffering and disability,affecting over 26 million people in the U.S., Europe, and Japan.

An anal fissure or ulcer is a tear or ulcer of the mucosa or liningtissue of the distal anal canal. An anal fissure or ulcer can beassociated with another systemic or local disease, but is morefrequently present as an isolated finding. The typical idiopathicfissure or ulcer is confined to the anal mucosa and usually lies in theposterior midline, distal to the dentate line. An individual with ananal fissure or ulcer frequently experiences anal pain and bleeding, thepain being more pronounced during and after bowel movements.

Hemorrhoids are specialized vascular areas lying subjacent to the analmucosa. Symptomatic hemorrhoidal diseases are manifested by bleeding,thrombosis and/or prolapse of the hemorrhoidal tissues. Commonly,internal hemorrhoidal tissue bulges into the anal canal duringdefecation and results in bleeding and pain. As the tissue enlarges,further bleeding, pain, prolapse and thrombosis can ensue. Thethrombosis of hemorrhoids is yet another cause of bleeding and pain.

Levator spasm is a condition affecting women more frequently than men.This syndrome is characterized by spasm of the levator ani muscle, aportion of the anal sphincter complex. The patient suffering fromlevator spasm may experience severe, episodic rectal pain. A physicalexam may reveal spasm of the puborectalis muscle and pain may bereproduced by direct pressure on this muscle. Bleeding is normally notassociated with this condition.

Hemorrhoids are the most prevalent anorectal disorder and are the mostcommon cause of hematochezia (i.e., passage of bloody stools).Hemorrhoidal disease is the consequence of distal displacement of theanal cushions, which normally play an important role in continence. Thecauses of hemorrhoids are not known. The most consistently demonstratedphysiological abnormality is increased resting anal pressure (Hancock B.D., Br J Surg 64(2):92-5 (1975); Loder, P. B., Br J Surg 81(7):946-54(1994)). Patients with non-prolapsing hemorrhoids appear to have higheranal pressures than those with prolapsing hemorrhoids (Arabi, Y. et al.,Am J Surg 134(5):608-10 (1977); Sun, W. M. et al., Br J Surg 77(4):458-62, (1990)), although the therapeutic implications of thisobservation remain unclear. Treatment is dependent on the degree ofhemorrhoid prolapse and symptoms. Most cases (first- and second-degreehemorrhoids) generally respond to conservative medical treatment (e.g.,dietary changes, sitz baths) or non-surgical procedures (e.g., rubberband ligation). Acutely thrombosed external hemorrhoids are usuallycharacterized by severe anal pain, and internal anal sphincterhypertonia may play a role in the etiology of this pain (Gorfine, S. P.,Dis Colon Rectum 38(5): 453-7 (1995)). Surgical excision of symptomaticthrombosed external hemorrhoids is indicated within 48 to 72 hours ofthe onset of pain. Post-hemorrhoidectomy pain is severe,disproportionate to the surgery itself, and requires the use of narcoticanalgesics, which unfortunately complicate recovery by causingconstipation. Anal dilatation and lateral internal sphincterotomy astreatments to reduce anal sphincter pressure in hemorrhoids have beenused successfully, both as stand alone procedures and in conjunctionwith hemorrhoidectomy (Keighley, M. R. et al., Br Med J J2(6196):967-9(1979); Schouten W. R. et al., Dis Colon Rectum 28(12), 869-72 (1986);Galizia et al., Eur J Surg 166(3):223-8 (2000)).

Others have reported that the addition of lateral internalsphincterotomy to routine hemorrhoidectomy is unnecessary and carriesthe added risk of incontinence (Mathai, V. et al., Br J Surg.83(3):380-2 (1996)).

Anal fissure is one of the most common causes of anorectal pain. Analfissures are tears in the mucosa of the distal anal canal, usually alongthe posterior midline. The exact causes of anal fissures remain unknown.They are often associated with trauma, e.g., passage of a hard stool,but can also occur during bouts of diarrhea, childbirth, or ulcerationof a hemorrhoid (Lund, J. N. et al., Br J Surg. 83(10): 1335-44 (1996)).The most common symptom is pain at defecation, which can be quite severeand last for a variable time afterwards. The pain is chiefly due to anintense spasm of the internal anal sphincter muscle. Most anal fissuresare adequately treated with sitz baths, stool softeners, and analgesics.Approximately 60% of acute anal fissures will heal within three weeksusing this treatment regimen. Acute anal fissures, which do not heal,become chronic anal fissures or anal ulcers. Hypertonicity of theinternal anal sphincter muscle and mucosal ischemia are thought to playan important role in the pathogenesis of chronic anal fissures (SchoutenW. R. et al., Dis Colon Rectum 37(7):664-9 (1994); Lund, J. N. et al.,Br J Surg 83(10): 1335-44(1996)). Anodermal blood flow at the posteriormidline is less than other regions of the anal canal, and perfusion ofthe posterior mucosa is inversely related to anal pressure. Chronic analfissures are typically not responsive to conservative medical therapy.Current treatments are therefore directed at relieving sphincter spasm,and include anal dilatation (under anesthesia), or more commonly,lateral sphincterotomy of the internal anal sphincter. Healing occursfollowing surgical sphincterotomy in 95% of cases. Successfulsphincterotomy (or anal dilatation) is associated with a significantdecrease in intra-anal pressure and increase in anodermal blood flow(Lund, J. N. et al., Br J Surg 83(10): 1335-44, (1996); Schouten W. R.et al., Scan J Gastroenterol. Suppl 218: 78-81 (1996)). However, up to35% of patients may experience some form of incontinence following thesurgical procedure (Sharp, F. R., Am J Surg 171(5):512-5 (1996)).Incontinence of stool and flatulence is a humiliating disability withnumerous social, medical, and financial implications. There is clearly alarge unmet medical need to develop effective, non-surgical treatmentsfor anal fissure and other colorectal conditions, including acutehemorrhoidal disease, hemorrhoidectomy pain, proctalgia fugax, andsevere constipation. Considerable recent progress has been made in theunderstanding of anorectal physiology and pharmacology. These newinsights provide important implications and opportunities for thepharmacological management of colorectal disorders.

Sphincters are circular groups of smooth muscle that control theorifices of hollow organs. They are present throughout thegastrointestinal tract and control the passage of materials through thissystem of the body. When constricted, sphincters close orifices leadingto or from the hollow organs, such as the stomach, intestine, rectum,etc. In order for the orifice to open, the sphincter must relax. The,sphincter that closes the anus (sphincter ani) consists of two sphinctermuscle groups. The external anal sphincter is a thin flat plane ofstriated muscle fibers adherent to the integument surrounding the marginof the anus. It is innervated by motor neurons and is under voluntarycontrol. The internal anal sphincter (IAS) is a ring of smooth musclethat surrounds the anal canal and is formed by a specialized aggregationof involuntary circular smooth muscle fibers of the intestine. The IASis largely responsible for resting anal sphincter pressure andcontinence which is maintained by intrinsic myogenic tone and regulatedby both intrinsic and extrinsic innervation from the autonomic nervoussystem (Penninckx, F. et al., Baillieres Clin Gastroenterol 6(1)193-214(1992); Speakman, C. T. Eur J Gastroenterol Hepatol 9(5):442-6 (1997)).

The IAS smooth muscle constantly generates rhythmic electrical slowwaves, but no action potentials. The slow waves are linked to calciumfluxes via voltage-dependent, L-type calcium channels that areresponsible for mechanical force generation and contraction of thesphincter. Accordingly, several calcium channel antagonists, includingdiltiazem and nifedipine, have been documented to reduce anal pressurein man (Jonard et al., Lancet 1(8535): 754 (1987); Chrysos, E. et al.,Dis Colon Rectum 39(2): 212-6 (1996); Antropoli, C. et al., Dis ColonRectum 42(8):1011-5 (1999); Carapeti, E. A. et al., Gut 45(5) 719-722(1999); Carapeti, E. A. et al., Br J Surg 86(2):267-70 (1999), and inseveral reports, to heal chronic anal fissures (Cook, T. A. et al., Br JSurg 86(10):1269-73 (1999); Brisinda, G. et al., Br J Surg 87(2): 251(2000)).

Sympathetic innervation of the IAS, supplied by the hypogastric nerves,is primarily excitatory and functions to enhance myogenic tone throughthe action of norepinephrine on smooth muscle α₁-adrenergic receptors(Frenckner, B., et al., Gut 17(4):306-12 (1976); Speakman, C. T. et al.,Dig Dis Sci 38(1.1)1961-9 (1993)). The α₁-adrenergic receptorantagonists phentolamine and indoramin reduce anal canal pressure whenadministered to healthy volunteers or patients with chronic analfissures (Speakrnan, C. T., Eur J Gastroenterology 9(5):442-6 (1997);Pitt, J. et al., Dis Colon Rectum 43(6)800-803 (2000)). Conversely, theα-receptor agonists methoxamine and phenylephrine increase anal pressure(Spealaan, C. T. 1997 supra; Carapeti, E. A. et al., Br J Surg86(2):267-70 (1999)). Low anal pressure is associated with incontinence(Speakman, C. T. Gastroenterology 9(5):442-6 (1997)). Speakman, C. T. etal., (Speakman, C. T. et al., Dig. Dis Sci. 38(11):1961-9 (1993))reported that the IAS of incontinent patients exhibit reducedsensitivity to norepinephrine. Although the α-adrenergic receptorpopulation is dominant, β-adrenergic receptors are also present on humanIAS, and mediate relaxation (Parks, A. G., et al., Gut 10(8):674-7(1969); Burleigh, D. E., et al., Gastroenterology 77(3): 484-90, (1979).The contractile response of the IAS to norepinephrine can be convertedto relaxation in the presence of selective α-receptor blockade, both invitro and in normal human volunteers (Burleigh, D. E., et al.,Gastroenterology 77(3): 484-90, (1979); Speakman, C. T., Eur JGastroenterology 9(5):442-6 (1997)). Regadas and colleagues (Regadas, F.S. et al., Br J Surg 80(6):799-801 (1993)) demonstrated that isolatedIAS strips from chronic anal fissure patients were significantly moresensitive to the relaxant effects of the β-adrenergic agonistisoproterenol than control tissues, whereas no differences were noted inthe contractile responses to phenylephrine and potassium chloride (amembrane depolarizing agent). However, it remains to be determinedwhether β-adrenergic agonists offer disease-specific advantages for thetreatment of chronic anal fissure.

The IAS relaxes in response to rectal distention (the rectoanalinhibitory reflex). The nerves mediating the rectoanal inhibitory reflexlie entirely within the wall of the gut (enteric inhibitory neurons),and descend from the rectum to the IAS. Electrical field stimulation(EFS) mimics the effects of intrinsic nerve stimulation on isolatedsmooth muscle strips. IAS strips are relaxed by EFS, an effect that isabolished by the neurotoxin tetrodotoxin, but is unaffected byantagonists of the classical neurotransmitters, acetylcholine ornorepinephrine. The inhibitory nerves are thus classified asnon-adrenergic, non-cholinergic (NANC) nerves. Adenosine triphosphate(ATP) and vasoactive intestinal peptide (VIP) were first suggested asNANC neurotransmitter candidates since they mimicked the relaxationelicited by electrical stimulation of motor nerve fibers (Burnstock, G.et al., Br J Pharmacol. 46(2):234-42 (1972); Bitar, K. N. et al.,Science 216(4545): 531-3 (1982)). However, ATP and VIP, eitherseparately or together, could not account for all inhibitoryneurotransmission in gastrointestinal smooth muscle, and their roleshave not been established in man (Burleigh, D. E. et al.,Gastroenterology 77(3): 484-90 (1979); Burleigh, D. E., J PharmPharmacol 35(4):258-60 (1983); Brookes, S. J., J Gastroenterol Hepatol8(6):590-603 (1993).

Recent studies indicate that NO plays an important role in NANC nervemediated relaxation of the IAS. In an animal model, Rattan, S. et al.,(Rattan, S. et al., Am J Physiol 262 (1 Pt 1):G107-12 (1992)demonstrated that IAS relaxation associated with the rectoanal reflex(induced by rectal balloon distention), or neural stimulation, wasblocked by inhibition of NO synthase (NOS) with L-NNA[N⁵-(nitroamidino)-L-2,5-diaminopentanoic acid], but not with D-NNA.Block of the rectoanal reflex by L-NNR was reversed by L-arginine in astereospecific manner, implicating NO or NO-like substances as mediatorsof NANC nerve mediated IAS relaxation. NO was shown to directly relaxthe IAS in a concentration-dependent manner in vitro, mimicking theeffect of NANC nerve stimulation by EFS. NANC nerve-mediated relaxationof LAS strips in vitro was blocked by inhibition of NO synthase withL-NNA, and the block was reversed by L-arginine, but not D-arginine(Rattan, S. et al., Am J Physiol 262 (1 Pt 1):G107-12, (1992) andRattan, S. et al., Gastroenterology 103(1):43-50 (1992)). Similarobservations have been made using isolated muscle strips of human IAS(Burleigh Gastroenterology 102(2): 679-83 (1992); O'Kelly, T. J. et al.,Br J Surg 80(10): 1337-41, (1993)). The direct release of NO followingNANC nerve stimulation of opossum LAS strips was demonstrated using aspecific chemiluminescence detection method (Chakder, S. et al., Am JPhysiol., 264 (4Pt 1)G702-7 (1993)). O'Kelly (O'Kelly, T. J. et al., DisColon Rectum 37(4): 35-7 (1994)) recently demonstrated the presence ofNOS in neurons of the myenteric plexus that project throughout the IASand lay in close proximity to smooth muscle cells. In Hirschsprung'sdisease, a condition in which the rectoanal reflex is absent, NOScontaining nerves were absent from the non-relaxing segment, but presentin the normal segment of the gut (O'Kelly, T. J. et al., J PediatricSurgery 29(2): 294-9 (1994)). These observations fulfill most of thecriteria for NO as an inhibitory mediator or neurotransmitter.

A number of potent vasodilators and smooth muscle relaxants are known tochemically release NO on or within target cells, and thus are known asNO donors. Some NO donors, e.g., nitroglycerin, are widely usedtherapeutically as coronary vasodilators to treat heart disease. Inkeeping with the role of NO as an inhibitory neurotransmitter mediatingrelaxation of the IAS, NO donors are beginning to be explored clinicallyas drugs to treat anal disorders associated with IAS hypertonicity.Significantly, nitroglycerin (Gorfine, S. R., Dis Colon Rectum,38(5):453-6 (1995); Watson, S. J. et al., Br J Surgery 83(6):771-5,1996; Lund, J. N. et al., Lancet 349: 9044 (1997)) and isosorbidedinitrate have been used to effect a reversible chemical sphincterotomyin patients with chronic anal fissure. These drugs reduce maximalresting anal pressure and, improve anodermal blood flow, reduce pain,and heal fissures in a majority of the patients. Nitroglycerin has alsobeen shown to reduce the throbbing pain of acute hemorrhoidal thrombosisand proctalgia fugax (Gorfine, S. R., Dis Colon Rectum 38(5):453-6(1995); Lowenstein, B. et al., Dis Colon Rectum 41(5):667-8 (1998)).

U.S. Pat. Nos. 5,504,117 and 5,693,676 describe the use of NO donors forthe treatment of anorectal conditions. However, the development ofadverse side effects such as the development of headaches has limitedthe use of NO donors in stand alone therapy, especially at higher doses.

One problem associated with topical nitroglycerin therapy, which maylimit its effectiveness, is the incidence of headache, particularly athigher doses (Palazzo, F. F. et al., J R Coll Surg Edinb 45(3): 168-70(2000)). The headache is presumably due to systemic effects ofnitroglycerin and is generally transient, but can affect patientcompliance. There is a need for treatment methods strategies whichenhance the local effect of nitroglycerin and minimize its systemic sideeffects. A second potential problem of nitrates is the development ofdrug tolerance, a problem well documented for nitrate therapy incardiovascular disease (Fung, H. L., et al., Cardiovasc Drugs Ther8(3):489-99, (1994)). Tolerance, if present, would limit the ability ofnitroglycerin to produce a sustained relaxation of the LAS, which may benecessary for healing particularly refractant chronic anal fissures.

There is clearly a significant need for other non-surgical treatments ofanorectal disorders, including, for example, anal fissures and otheranorectal conditions caused by anal sphincter spasm and orhypertonicity, including acute-hemorrhoidal diseases and proctalgiafugax.

There is thus a need for alternative methods and compositions forreducing anal sphincter pressure that complement or supplantnitroglycerin.

The use of a topical or intra-rectal pharmaceutical preparation thatcomplements or supplants nitroglycerin for the treatment of chronic analfissures and other anorectal disorders can provide the first effectivealternative to surgery for this painful disorder.

BRIEF SUMMARY OF THE INVENTION

In one aspect, the present invention provides compositions for thetreatment of anorectal disorders comprising a nitric oxide donor incombination with a second agent (typically one which modulates levels ofcAMP or cGMP). The second agent can be a phosphodiesterase type V (PDEV) inhibitor, a phosphodiesterase type II (PDE II) inhibitor, aphosphodiesterase type IV (PDE IV) inhibitor, a nonspecific PDEinhibitor, a β-adrenergic agonist, a cAMP-dependent protein kinaseactivator, an estrogen or estrogen-like compound, or an α₁-adrenergicantagonist. The agent can also be a superoxide anion (O₂ ⁻) scavenger,an ATP-sensitive K⁺ channel activator, a sympathetic nerve terminaldestroyer, or a smooth muscle relaxant, although these agents do notdirectly modulate either cAMP or cGMP levels. The present inventionfurther provides methods of using these compositions.

In another aspect, the present invention provides compositions for thetreatment of anorectal disorders comprising a phosphodiesteraseinhibitor, preferably a PDE II inhibitor, a PDE IV inhibitor or a PDE Vinhibitor, either alone or in combination with another agent selectedfrom β-adrenergic receptor agonists, α₁-adrenergic antagonists,estrogens, L-type Ca²⁺ channel blockers, ATP-sensitive K⁺ channelactivators, or smooth muscle relaxants, in combination with apharmaceutically acceptable carrier. The present invention also providesmethods of using these compositions.

In another aspect, the present invention provides compositions for thetreatment of anorectal disorders comprising a β-adrenergic receptoragonist, preferably a β₂- or β₃-adrenergic receptor agonist, eitheralone or in combination with another agent selected fromcAMP-hydrolyzing PDE inhibitors (e.g., a PDE IV inhibitor), nonspecificPDE inhibitors, α₁-adrenergic antagonists, estrogens or estrogen-likecompounds, L-type Ca²⁺ channel blockers, or ATP-sensitive K⁺ channelactivators, and methods of using those compositions.

In yet another aspect, the present invention provides compositions forthe treatment of anorectal disorders comprising an ATP-sensitive K⁺channel activator, either alone or in combination with another agentselected from cAMP-dependent protein kinase activators, α₁-adrenergicantagonists, estrogens, L-type Ca²⁺ channel blockers, or smooth musclerelaxants, and methods of using those compositions.

In still another aspect, the present invention provides compositions forthe treatment of anorectal disorders comprising an α₁-adrenergicantagonist, either alone or in combination with another agent selectedfrom cAMP-hydrolyzing PDE inhibitors (preferably a PDE IV inhibitor) orsmooth muscle relaxants, and methods of using those compositions.

In another aspect, the present invention provides compositions for thetreatment of anorectal disorders comprising β₂-adrenergic agonists,either alone or in combination with another agent. Methods for the useof these compositions are also provided. In one group of embodiments,the β₂-adrenergic agonists are used alone. In a preferred embodiment,the β₂-adrenergic agonists is combined with a phosphodiesteraseinhibitor. In another embodiment, the β₂-adrenergic agonists arecombined with one or more other IAS relaxing agents.

In another aspect, the present invention provides compositions for thetreatment of anorectal disorders comprising adenosine receptorantagonists, either alone or in combination with another agent. Methodsfor the use of these compositions are also provided. In one group ofembodiments, adenosine receptor antagonists are used alone. In anothergroup of embodiments, the adenosine receptor antagonists are combinedwith at least one other IAS relaxing agent.

In another aspect, the present invention provides compositions for thetreatment of anorectal disorders comprising cyclic nucleotide-dependentprotein kinase activators, either alone or in combination with anotheragent. Methods for the use of these compositions are also provided. Inone group of embodiments, cGMP-dependent protein kinase activators areused alone. In another group of embodiments, nonspecific cyclicnucleotide-dependent protein kinase activators are used alone. In yetanother group of embodiments, nonspecific cyclic nucleotide-dependentprotein kinase activators are used in combination with smooth musclerelaxants. In still another group of embodiments, cAMP-dependent proteinkinase activators are provided in combination with L-type Ca²⁺ channelblockers.

In yet another aspect, the present invention provides a composition forthe treatment of anorectal disorders comprising a methylxanthinecompound. In preferred embodiments, the compound is theophylline ordyphylline. In still another embodiment, the methylxanthine compound isused alone. In still another embodiment, the methylxanthine compound iscombined with another IAS relaxing agent.

In yet another aspect, the present invention provides compositions forthe treatment of anorectal disorders comprising an estrogen or otherestrogenic compound, either alone or in combination with another agent.Methods for the use of these compositions are also provided. In onegroup of embodiments, estrogenic compounds are used alone. In anothergroup of embodiments, the estrogenic compounds are used in combinationwith a second agent selected from phosphodiesterase inhibitors,β-adrenergic receptor agonists, α₁-adrenergic antagonists, L-type Ca²⁺channel blockers, ATP-sensitive K+ channel activators, or smooth musclerelaxants, in combination with a pharmaceutically acceptable carrier.The present invention further provides methods of using thesecompositions.

Where the compounds discussed above act through mechanisms distinctlydifferent from nitroglycerin, they can be used to complementnitroglycerin therapy, or as stand alone products.

As noted above, methods of treating anorectal disorders are alsoprovided herein. The methods of the invention comprise administering toa subject a suitable formulation of one or more of the compositionsabove. In related methods, treatment is carried out by administration oftwo or more agents in sequence, either by the same route ofadministration or by different routes of administration.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a typical waveform pattern for resting IASP in a ratunder conditions of a control experiment.

FIG. 2 illustrates the waveform pattern for IASP in a rat followingadministration of 20 μl of a 1% solution of nitroglycerin in propyleneglycol.

FIG. 3 illustrates the effect of a cGMP mimetic on internal analsphincter pressure in a rat. The figure shows a waveform pattern forIASP for a rat following administration of 20 μL of a 10% solution ofdibutyryl-cGMP in saline.

FIG. 4 illustrates the effect of a type V phosphodiesterase inhibitor oninternal anal sphincter pressure in a rat. The figure shows a waveformpattern for IASP for a rat following administration of 20 μl of a 5%solution of zaprinast in 1-methyl-2-pyrrolidinone.

FIG. 5 illustrates the effect of a potassium channel opener on internalanal sphincter pressure in a rat. The figure shows a waveform patternfor IASP for a rat following administration of 20 μl of a 4% solution ofminoxidil in 62.5% propylene glycol.

FIG. 6 illustrates the effect of NTG administered to the IAS as a bolusdose.

FIG. 7 illustrates the effect of NTG administered to the IAS bycontinuous infusion over 4 hours.

FIG. 8 illustrates the effect of 8-bromo cAMP infused to the IAS at 20μg/hour for three hours.

FIG. 9 illustrates the effect of dibutyryl cAMP infused to the IAS at 20μg/hour for three hours.

FIG. 10 illustrates the effect of a bolus delivery of SOD (200 μg) tothe IAS, followed by a bolus dose of NTG (200 μg) in the same vehicle.

FIG. 11 illustrates the effect of a bolus delivery of NTG (200 μg) tothe IAS, followed by a bolus dose of SOD (200 μg) in the same vehicle.

FIG. 12 illustrates the effect on the LAS of a vehicle injectionfollowed after 30 minutes by bolus doses of NTG.

FIG. 13 illustrates the effect on the IASP of an i.p. injection ofzaprinast followed by bolus doses of NTG applied topically to the IAS.

FIG. 14 illustrates the effect on the IASP of a bolus dose of NTGapplied topically to the IAS, wherein the first NTG dose is provided at2.75 hours after a vehicle injection.

FIG. 15 illustrates the effect on the IASP of an i.p. injection ofzaprinast followed by bolus doses of NTG, wherein the first NTG dose isprovided at 2.75 hours after zaprinast injection.

FIG. 16 illustrates the effect on the IAS of a vehicle injectionfollowed after 50 minutes by bolus doses of NTG.

FIG. 17 illustrates the effect on the IAS of PDE V inhibitor,dipyridamole injected i.p. 50 minutes prior to bolus doses of NTG.

FIG. 18 illustrates the effect on the IASP of PDE V inhibitor MBCQinjected i.p. 30 minutes prior to bolus doses of NTG.

FIG. 19 illustrates the effect on the IASP of β-agonist isoproterenoldelivered to the IAS 30 minutes after saline alone.

FIG. 20 illustrates the effect on the IASP of β₂-agonist terbutaline insaline infused continuously at 20 μg/hour.

FIG. 21 illustrates the effect on the IASP of β₂-agonist salbutamol insaline infused continuously at 20 μg/hour.

FIG. 22 illustrates the effect on the IASP of PDE IV inhibitor rolipramin DMSO/acetone/olive oil infused continuously at 20 μg/hour.

FIG. 23 illustrates a bolus dose of salbutamol followed by a singlebolus dose of salbutamol and PDE IV inhibitor etazolate.

FIG. 24 illustrates a bolus dose of etazolate followed by a single bolusdose of salbutamol and etazolate.

FIG. 25 illustrates the effect on the IASP of PDE IV inhibitor Ro20-1724 in DMSO/acetone/olive oil infused continuously at 20 μg/hour.

FIG. 26 illustrates a vehicle control for the treatments provided inFIG. 27.

FIG. 27 illustrates the effect on the IASP of the specific adenylcyclase activator forskolin, in DMSO/acetone/olive oil infusedcontinuously at 20 μg/hour.

FIG. 28 illustrates the effect on the IASP of the α₁-blocker, prazosin,in DMSO/acetone/olive oil infused continuously at 20 μg/hour.

FIG. 29 illustrates the effect on the IASP of the nonspecific PDEinhibitor IBMX, in DMSO/acetone/olive oil infused continuously at 200μg/hour.

FIG. 30 illustrates the effect on the IASP of the nonspecific PDEinhibitor IBMX, in DMSO/acetone/olive oil infused continuously at 20μg/hour.

FIG. 31 illustrates the effect on the IASP of a single bolus dose of theK⁺-ATP channel opener minoxidil in propylene glycol/water.

FIG. 32 illustrates the effect on the IASP of the K⁺-ATP channel openerdiazoxide, in DMSO/acetone/olive oil infused continuously at 20 μg/hour.

FIG. 33 illustrates the effect on the IASP of the Ca⁺²-channel blockerdiltiazem in saline infused continuously at 20 μg/hour.

FIG. 34 illustrates the effect on the IASP of the Ca⁺²-channel blockerverapamil in saline infused continuously at 20 μg/hour.

FIG. 35 illustrates the effect on the IASP of the sympathetic nerveterminal destroyer 6-hydroxydoparmine when administered to the LAS inbolus doses of 200 μg per day for 5 days.

FIG. 36 illustrates the effect on the IASP of a control vehicle i.pinjection of 1-methyl-2-pyrollidinone followed after 30 minutes bycontinuous infusion of a sub-threshold dose of isoproterenol in saline(0.2 μg/hour).

FIG. 37 illustrates the effect on the IASP of the PDE III/WW inhibitorzardaverine when injected i.p. (10 mg in vehicle) followed after 30minutes by a continuous infusion of isoproterenol.

FIG. 38 illustrates the effect on the IASP of the PDE III/W inhibitorzardaverine when injected i.p. (7.5 mg in vehicle) followed after 30minutes by a continuous infusion of 5% dextrose.

FIG. 39 illustrates the effect on the LASP of the PDE III/IV inhibitorzardaverine when injected i.p. (7.5 mg in vehicle) followed after 30minutes by a continuous infusion of a sub-threshold dose ofisoproterenol.

FIG. 40 illustrates the effect on the IASP of the adenosine antagonistand non-specific PDE inhibitor, theophylline when continuously infusedat 200 μg/hour in 5% dextrose.

FIG. 41 illustrates the effect on the IASP of theophylline whencontinuously infused at 20 μg/hour in 5% dextrose.

FIG. 42 illustrates the effect on the IASP of theophylline whencontinuously infused at 2 μg/hour in 5% dextrose.

FIG. 43 illustrates the effect on the IASP of dyphylline whencontinuously infused at 20 μg/hour in 5% dextrose.

DETAILED DESCRIPTION OF THE INVENTION

Abbreviations and Definitions

cAMP, cyclic adenosine monophosphate; cGMP, cyclic guanosinemonophosphate; NO, nitric oxide; NTG, nitroglycerin; SOD, superoxidedismutase; PDE, phosphodiesterase; IASP, internal anal sphincterpressure; Rp-cAMPS, Rp-Adenosine-3′,5′-cyclic monophosphorothioate;Sp-cAMPS, Sp-Adenosine-3′,5′-cyclic monophosphorothioate; 8-CPT cAMP,8-(4-Chlorophenylthio)-adenosine-3′,5′-cyclic monophosphate, sodiumsalt; Sp-5,6-DCI-cBiMPS,Sp-5,6-dichloro-1-b-D-ribofuranosylbenzimidazole-3′,5′-monophosphorothioate;Dibutyryl-cAMP, N6,2′-O-Dibutyryladenosine-3′,5′-cyclic monophosphate,sodium salt monohydrate; Sp-8-pCPT-cGMPS,Sp-8-(4-Chlorophenylthio)-quanosine-3′,5′-cyclic monophosphate, sodiumsalt; 8-Bromo-cGMP, 8-Bromoguanosine-3′,5′-cyclic monophosphate, sodiumsalt; Rp-8-Br-cGMPS, Rp-8-Bromoguanosine-3′,5′-cyclicmonophosphorothioate, sodium salt; Dibutyryl-cGMP,N2,2′-O-Dibutyrylguanosine-3′,5′-cyclic monophosphate, sodium salt;EHNA, erythro-9-(2-Hydroxy-3-nonyl)adenine HCI; IBMX,3-Isobutyl-1-methylxanthine; MY-5445,1-(3-Chlorophenylamino)-4-phenylphthalazine; Ro 20-1724,4-(3-Butoxy-4-methoxybenzyl)-2-imidazolidinone; MBCQ,4-((3,4-(Methylenedioxy)benzyl)amino)-6-chloroquinazoline.

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as commonly understood by those of ordinary skillin the art to which this invention belongs. The following referencesprovide one of skill with a general definition of many of the terms usedin this invention: Singleton et al., DICTIONARY OF MICROBIOLOGY ANDMOLECULAR BIOLOGY (2d ed. 1994); THE CAMBRIDGE DICTIONARY OF SCIENCE ANDTECHNOLOGY (Walker ed., 1988); and Hale & Marham, THE HARPER COLLINSDICTIONARY OF BIOLOGY (1991). As used herein, the following terms havethe meanings ascribed to them unless specified otherwise. Although anymethods and materials similar or equivalent to those described hereinmay be used in the practice or testing of the present invention, thepreferred methods and materials are described. For purposes of thepresent invention, the following terms are defined below.

The terms “treatment”, “therapy” and the like include, but are notlimited to, changes in the recipient's status. The changes can be eithersubjective or objective and can relate to features such as symptoms orsigns of the disease or condition being treated. For example, if thepatient notes decreased itching, reduced bleeding, reduced discomfort ordecreased pain, then successful treatment has occurred. Similarly, ifthe clinician notes objective changes, such as by histological analysisof a biopsy sample, then treatment has also been successful.Alternatively, the clinician may note a decrease in the size of lesionsor other abnormalities upon examination of the patient. This would alsorepresent an improvement or a successful treatment. Preventing thedeterioration of a recipient's status is also included by the term.Therapeutic benefit includes any of a number of subjective or objectivefactors indicating a response of the condition being treated asdiscussed herein.

“Drug”, “pharmacological agent”, “pharmaceutical agent”, “active agent”,and “agent” are used interchangeably and are intended to have theirbroadest interpretation as to any therapeutically active substance whichis delivered to a living organism to produce a desired, usuallybeneficial effect.

“Pharmaceutically-acceptable” or “therapeutically-acceptable” refers toa substance which does not interfere with the effectiveness or thebiological activity of the active ingredients and which is not toxic tothe hosts, which may be either humans or animals, to which it isadministered. “Therapeutically-effective amount” refers to the amount ofan active agent sufficient to induce a desired biological result. Thatresult may be alleviation of the signs, symptoms, or causes of adisease, or any other desired alteration of a biological system. Theterm “therapeutically effective amount” is used herein to denote anyamount of the formulation which causes a substantial improvement in adisease condition when applied to the affected areas repeatedly over aperiod of time. The amount will vary with the condition being treated,the stage of advancement of the condition, and the type andconcentration of formulation applied. Appropriate amounts in any giveninstance will be readily apparent to those skilled in the art or capableof determination by routine experimentation.

The term “anorectal area” is defined herein to include both the anus andthe rectum region of a mammal. More particularly, the term includes theinternal anal canal, the external anus and the lower rectum.

“Hypertonicity” refers to being in state of greater than normal musculartension or of incomplete relaxation.

The term “cyclic nucleotide” refers to cyclic adenosine monophosphateand cyclic guanosine monophosphate.

The term “modulation” refers to any systematic variation or gradedchange in a characteristic (e.g. frequency, concentration, amplitude,effectiveness, etc.) of a sustained oscillation sufficient to affect abiological function. The term “change” includes an increase or decreasein the characteristic.

The term “subject” as used herein includes any animal, such as a mammal,including a human.

The term “anorectal disorder” includes any disorder associated with ananal rectal disease, including an acute or chronic anal fissure, aninternally or externally thrombosed hemorrhoid, a hemorrhoidal disease,a disorder associated with endoscopic hemorrhoidal ligation or paincaused by such ligation, levator spasm, constipation, and otheranorectal disorder caused by hypertonicity or spasm of the analsphincter muscle. The term also refers to post-surgical pain associatedwith hemorrhoidectomy or other anorectal surgery that leads to intenseanal spasms. The term “anal fissure” is also referred to as “analrhagades” and spasms of the anal sphincter are also referred to as“rectal tenesmus.” Additionally, the term is meant to include pain whichcan be associated with any of the above disorders or conditions.

The terms “signs, symptoms and causes of anorectal disease” and “signsand symptoms of anorectal disease” include, but are not limited to, analsphincter hypertonicity; anal and rectal ischemia, itching,inflammation, pain or bleeding; thrombosed or prolapsed hemorrhoidaltissue; spasticity of the levator ani muscle, spasm of the puboretalismuscle or anal sphincter muscles, and linear or ischemic ulcers orcrack-like sores in the anal canal or on the margin of the anus.

The term “desirable therapeutic effects” in the treatment of anorectaldiseases and conditions includes, but is not limited to, anal sphincterrelaxation; reduction of anal sphincter pressure; maintenance of reducedanal sphincter pressure; reduction or elimination of ischemia, itching,inflammation, pain, bleeding, or muscle spasm; restoration orimprovement of anoderm blood flow; dilation of blood vessels in the anusand rectum; and partial or complete healing of linear or ischemic ulcersor crack-like sores in the anal canal or on the margin of the anus.

The terms “potassium channel opener” and “potassium channel activator”refer generally to a class of drugs that cause an increased flow ofpotassium ions from inside an electrically excitable cell to outside thecell via a membrane of the cell which has at least one potassiumchannel. Potassium channel opener activity may be observed by measuringa hyperpolarization of the cell membrane potential (i.e. a more negativemembrane potential) caused by an increase in the flow of potassium ionsfrom inside a cell to outside the cell via a potassium channel in thecell membrane.

The term “pharmaceutical composition” means a composition suitable forpharmaceutical use in a subject, including an animal or human. Apharmaceutical composition generally comprises an effective amount of anactive agent and a pharmaceutically acceptable carrier.

The term “pharmaceutically acceptable carrier” encompasses any of thestandard pharmaceutical carriers, buffers and excipients, includingphosphate-buffered saline solution, water, and emulsions (such as anoil/water or water/oil emulsion), and various types of wetting agentsand/or adjuvants. Suitable pharmaceutical carriers and theirformulations are described in REMINGTON'S PHARMACEUTICAL SCIENCES (MackPublishing Co., Easton, 19th ed. 1995). Preferred pharmaceuticalcarriers depend upon the intended mode of administration of the activeagent. Typical modes of administration are described below.

The term “effective amount” means a dosage sufficient to produce adesired result. The desired result may comprise a subjective orobjective improvement in the recipient of the dosage.

A “prophylactic treatment” is a treatment administered to a subject whodoes not exhibit signs of a disease or exhibits only early signs of adisease, wherein treatment is administered for the purpose of decreasingthe risk of developing pathology.

A “therapeutic treatment” is a treatment administered to a subject whoexhibits signs of pathology, wherein treatment is administered for thepurpose of diminishing or eliminating those pathological signs.

The term “appropriate anal area” means any area or tissue of the anus orsphincter that is affected by or subject to anal disorder or disease,including, for example, the external or internal anus, the external orinternal anal sphincter, anal sphincter muscle, or external or internalanal canal.

As used herein, the term “NO donor” refers to any organic or inorganiccompound that can deliver nitric oxide in a physiologic setting. Alsoincluded are those compounds that can be metabolized in vivo into acompound which delivers nitric oxide (e.g., a prodrug form of a NOdonor, or a binary NO generating system).

General

A promising new approach for treating anal disorders is the topicalapplication of a nitric oxide (NO) donor to an appropriate anal area.Nitric oxide has been shown to bring about a concentration-dependentreduction in the resting tension of internal sphincter smooth musclestrips in vitro (Rattan, S. et al., Am J Physiol 262:G107-112 (1992)),and NO donors (e.g., nitroglycerin, isosorbide dinitrate, isosorbidemononitrate, and L-arginine) have been shown to reduce anal pressure inhumans. Schouten, W. R. et al., “Pathophysiological aspects and clinicaloutcome of intra-anal application of isosorbide dinitrate in patientswith chronic anal fissure,” Gut 39:465-9 (1996); Farid, M., Br J Surg84:1 (1997); and Hechtman, H. B. et al., Arch. Surg 131:775-778 (1996).NO has also been shown to mediate adaptive relaxation of othersphincters in the gastrointestinal tract including the lower esophagealsphincter (Conklin et al., Gastroenterology 104:1439-1444 (1993);Tottrup et al., Br J Pharmacol 104:113-116 (1991)), pyloric sphincter(Bayguinov et al., Am J Physiol 264:G975-983 (1993), sphincter of Oddi(Mourelle et al., Gastroenterology 105:1299-1305 (1993)), and theileocolic sphincter (Ward et al., Br J Pharmacol 105:776-782 (1992)). Itis thought that NO or NO-like substances serve as important controlmechanisms for the general phenomenon of gastrointestinal adaptiverelaxation.

Despite the initial promise of NO donors, tachyphylaxis has beenobserved for members of this class of agents. Surprisingly, the presentinvention provides compositions which are useful to overcome sideeffects and problems associated with the current therapies.

DESCRIPTION OF THE EMBODIMENTS

NO Donors in Combination with a Second Agent

In one aspect, the present invention provides compositions for thetreatment of anal disorders comprising a nitric oxide donor incombination with a second agent which modulates levels of cAMP or cGMP.In one group of embodiments the second agent is a phosphodiesterase typeV (PDE V) inhibitor. In another group of embodiments the second agent isa phosphodiesterase type IV (PDE IV) inhibitor. In another group ofembodiments the second agent is a phosphodiesterase type II (PDE II)inhibitor. In another group of embodiments the second agent is anonspecific PDE inhibitor. In still another group of embodiments thesecond agent is a superoxide anion (O₂ ⁻) scavenger. In yet anothergroup of embodiments the second agent is a β-adrenergic agonist. Inanother group of embodiments, the second agent is a cAMP-dependentprotein kinase activator. In another group of embodiments the secondagent is an α₁-adrenergic antagonist. In another group of embodimentsthe second agent is an estrogen, estrogen analog, or estrogeniccompound. In another group of embodiments the second agent is an L-typeCa²⁺ channel blocker. In still another group of embodiments the secondagent is an ATP-sensitive K⁺ channel activator. The present inventionfurther provides methods of using the compositions provided above. In arelated aspect, the present invention provides compositions comprising aNO donor and a smooth muscle relaxant.

In each of the above embodiments, the nitric oxide donor can be any of avariety of NO donors including, for example, organic NO donors,inorganic NO donors and prodrug forms of NO donors. Preferably, the NOdonor includes at least one organic nitrate (including esters of nitricacid) and can be either a cyclic or acyclic compound. For example,suitable NO donors include nitroglycerin (NTG), L-arginine, isosorbidedinitrate (ISDN), isosorbide mononitrate (ISMN) which may includeisosorbide-2-mononitrate (IS2MN) and/or isosorbide-5-mononitrate(IS5MN), erythrityl tetranitrate (ETN), pentaerythrityl tetranitrate(PETN), ethylene glycol dinitrate, isopropyl nitrate,glyceryl-1-mononitrate, glyceryl-1,2-dinitrate, glyceryl-1,3-dinitrate,butane-1,2,4-triol trinitrate, and the like. More preferably, the NOdonor is NTG. Nitroglycerin and other organic nitrates including ISDN,ETN, and PETN, have been given regulatory approval for use in treatmentsin other fields of medicine on human subjects. Additional NO donorsinclude sodium nitroprusside,N,O-diacetyl-N-hydroxy-4-chlorobenzenesulfonamide,N^(G)-hydroxy-L-arginine (NOHA), hydroxyguanidine sulfate, molsidomine,3-morpholinosydnonimine (SIN-1), (±)-S-nitroso-N-acetylpenicillamine(SNAP), S-nitrosoglutathione (GSNO),(±)(E)-ethyl-2-[(E)-hydroxyimino]-5-nitro-3-hexeneamide (FK409),(±)-N-[(E)-4-ethyl-3-[(Z)-hydroxyimino]-5-nitro-3-hexen-1-yl]-3-pyridinecarboxamide(FR144420), and 4-hydroxymethyl-3-furoxancarboxamide.

In general, the organic nitric oxide donor (e.g., the organic nitrate)is present in any amount less than that which is effective in thepractice of the treatment of anal disease when used alone. In typicalpractice of the invention the organic nitric oxide donor can be presentin a concentration from about 0.01 to about 10 percent by weight. Allweight percentages herein are based on the total weight of thecomposition. For NTG, preferred concentrations are in the range of fromabout 0.01 to about 5 percent by weight.

In one group of embodiments, the composition contains an agent which isa phosphodiesterase (PDE) inhibitor. Inhibitors of phosphodiesterases(PDE), are agents which can block the breakdown of cAMP and cGMP in thetissue. PDE inhibitors include both non-specific PDE inhibitors andspecific PDE inhibitors (those which inhibit a single type ofphosphodiesterase with little, if any, effect on any other type ofphosphodiesterase). Still other useful PDE inhibitors are the dualselective PDE inhibitors (e.g., PDE III/IV inhibitors).

In one group of embodiments, the PDE inhibitor is a PDE V inhibitor.Useful phosphodiesterase type V inhibitors include zaprinast, MBCQ,MY-5445, dipyridamole and sildenifil.

In another group of embodiments, the composition contains an agent whichis a phosphodiesterase type II (PDE II) inhibitor. Suitablephosphodiesterase type II inhibitors include EHNA.

In yet another group of embodiments, the composition contains an agentwhich is a phosphodiesterase type IV (PDE IV) inhibitor. Suitablephosphodiesterase type IV inhibitors include ariflo (SB207499), RP73401,Ro-201724, CDP840, rolipram and LAS31025.

In still another group of embodiments, the composition contains an agentwhich is a dual selective phosphodiesterase inhibitor, preferably a PDEIII/IV inhibitor such as, for example, zardaverine.

In yet another group of embodiments, the composition contains an agentwhich is a nonspecific phosphodiesterase (nonspecific PDE) inhibitor.Suitable nonspecific phosphodiesterase inhibitors include IBMX,theophylline, dyphylline theobromine, aminophylline, pentoxifylline,papaverine, caffeine and other methyl xanthine and non-xanthinederivatives (Goodman & Gilman's “The Pharmacological Basis ofTherapeutics” The McGraw-Hill Companies, 1996).

In still another group of embodiments, the composition contains an agentwhich is a superoxide anion (O₂ ⁻) scavenger. Superoxide can react withNO and dramatically reduce its biological effects. Accordingly, agentsthat scavenge superoxide anion (e.g., exogenous Mn- or Cu/Zn superoxidedismutase (SOD) or small molecule SOD mimetics, e.g. Mn(III)tetra(4-benzoic acid) porphyrin chloride (MnTBAP) and M40403, seeSalvemini, et al., Science 286(5438):304-306 (1999)) can enhance theeffects of NO. SODs are relatively stable enzymes and can be used intopical formulations with NO donors such as, for example, NTG, to boostthe local potency of NO generated from NTG. The nitric oxide formed fromNTG acts only locally due to its short half-life. However, NTG itself isstable enough to exert systemic effects following mucosal absorption. Byenhancing the local efficacy of NTG with SOD or a SOD mimetic, less NTGis required to produce the same degree of internal anal sphincterrelaxation, and less NTG is absorbed, leading to a reduction in systemicside effects.

In yet another group of embodiments, the composition contains an agentwhich is a β-adrenergic agonist, preferably a β₂- or β₃-adrenergicreceptor agonist. A variety of β-adrenergic agonists have been describedin the literature and are useful in the present invention. Suitableβ₃-adrenergic agonists are described in, for example, Bristol, et al.,ANNUAL REPORTS IN MEDICINAL CHEMISTRY, VOL. 33, Chap. 19, pp 193-202,Academic Press (1998). Preferred β-adrenergic agonists includesalbutamol, terbutaline, procaterol, clenbuterol, isoproterenol,zinterol, BRL 37344, CL316243, CGP-12177A, GS 332, L-757793, L-760087,L-764646, and L-766892.

In another group of embodiments, the agent is a cAMP-dependent proteinkinase activator. A variety of cyclic nucleotide-dependent proteinkinase activators are useful in the present invention including, forexample, cAMP mimetics and dual cGMP/cAMP-dependent protein kinaseactivators. cAMP mimetics are well known to those of skill in the artand include 8-bromo-cAMP, dibutyryl-cAMP, Rp-cAMPS, and Sp-cAMPS. Dualactivators include Sp-8-pCPT-cGMPS, Sp-8-bromo-cGMPS and 8-CPT-cAMP.

In yet another group of embodiments, the composition contains an agentwhich is an estrogen or estrogen analog or mimetic. As used herein, theterm “estrogens” is meant to include all forms of estrogen andestrogen-like compounds such as those compounds having estrogen likeactivity (e.g., those which bind to the estrogen receptor in acompetitive binding assay). The estrogens can be either steroidal ornonsteroidal (see, for example, Bristol, et al., ANNUAL REPORTS INMEDICINAL CHEMISTRY, VOL. 31, Chap. 19, pp 181-190, Academic Press(1996), and references cited therein). Estrogen-like compounds includebut are not limited to 17-beta-estrodiol, estrone, mestranol, estradiolvalerate, estrodiol dypionate, ethinyl estrodiol, quinestrol, estronesulfate, phytoestrogens such as flavones, isoflavones (e.g. genistein),resveratrol, coumestan derivatives, other synthetic estrogenic compoundsincluding pesticides (e.g. p,p′-DDT), plasticizers (e.g. bisphenol A),and a variety of other industrial chemicals (e.g. polychlorinatedbiphenyls).

In yet another group of embodiments, the composition contains an agentwhich is an α₁-adrenergic antagonist. The sympathetic neurotransmitternorepinephrine contracts sphincter smooth muscle via α₁-adrenergicreceptors. Pharmacological interference with norepinephrine release orbinding to α₁-adrenergic receptors by administering sympatholytic agentsto the appropriate anal area of a subject can also lead to analsphincter relaxation, reduction of anal sphincter pressure, maintenanceof reduced anal sphincter pressure, and improvement of the signs andsymptoms of anorectal disorders. Such sympatholytic agents includeα₁-adrenergic receptor antagonists (e.g. prazosin, doxazosin,phentolamine, tolazoline, and the like as described in Goodman &Gilman's THE PHARMACOLOGICAL BASIS OF THERAPEUTICS, ninth edition, ed. JG Hardman, et al., McGraw-Hill 1996), α₂-adrenergic agonists which blocknorepinephrine release (e.g. clonidine), nerve terminal norepinephrinedepleting agents (e.g. guanethidine, bretylium, reserpine),norepinephrine synthesis inhibitors (e.g. α-methyl tyrosine), and agentswhich destroy sympathetic nerve terminals (e.g. 6-hydroxy dopamine).Accordingly, in a related embodiment, the composition contains analternative sympatholytic agent, such as an α₂-adrenergic receptoragonist, a nerve terminal norepinephrine depleting agent, anorepinephrine synthesis inhibitor or another agent which destroyssympathetic nerve terminals.

In still another group of embodiments the agent is an ATP-sensitive K⁺channel activator. ATP, along with NO, is thought to serve as aninhibitory neurotransmitter released from the enteric non-adrenergic,non-cholinergic nerves that mediate adaptive relaxation ofgastrointestinal smooth muscle (Burnstock, Pharmacol Rev. 24:509-81(1972)). ATP appears to act primarily by opening ATP-sensitive potassium(K_(ATP)) channels which hyperpolarize the cell membrane, reducingintracellular calcium concentrations, leading to smooth musclerelaxation. Synthetic compounds that activate ATP-sensitive K+ channelsare smooth muscle relaxants, e.g. minoxidil, minoxidil sulfate,pinocidil, diazoxide, levcromokalim, cromakalim, etc. (see White, etal., Eur J Pharmacol. 357(1):41-51 (1998)). ATP-sensitive potassiumchannels are expressed in GI smooth muscle (Koh, et al., Biophys. J.75:1793-80 (1998)). Accordingly, specific potassium channel openers willbe useful for relaxing internal anal sphincter smooth muscle, reducinganal sphincter pressure, maintaining reduced anal sphincter pressure,and improving the signs and symptoms of anorectal disorders. It shouldbe noted that other K⁺ channels can also influence smooth muscle tone,including apamin-sensitive low conductance calcium-activated K⁺ channelsand charybdotoxin-sensitive high conductance calcium-activated K⁺channels.

In still other embodiments, the compositions will comprise NO donors andsmooth muscle relaxants. Preferred smooth muscle relaxants include, forexample, hydralazine, papaverine, tiropramide, cyclandelate, isoxsuprineor nylidrin.

In yet other embodiments, the compositions will comprise NO donors and asecond agent which is a methyl xanthine or adenosine receptorantagonist. Preferred second agents include theophylline, dyphylline,aminophylline, caffeine, and theobromine.

In a preferred embodiment, a second agent is a K⁺ ATP channel opener, anadenosine receptor antagonist, or a β2-adrenergic receptor agonist. Inyet further embodiments, a second agent is preferably selected from thegroup consisting of theophylline, dyphylline, minoxidil, diazoxide,terbutaline, and salbutamol.

Phosphodiesterase Inhibitor Compositions

In another aspect, the present invention provides compositions for thetreatment of anorectal disorders comprising a phosphodiesteraseinhibitor, preferably a PDE II inhibitor, a PDE IV inhibitor or a PDE Vinhibitor, either alone or in combination with another agent selectedfrom β-adrenergic receptor agonists, α₁-adrenergic antagonists,estrogens, L-type Ca²⁺ channel blockers, ATP-sensitive K⁺ channelactivators, or smooth muscle relaxants, in combination with apharmaceutically acceptable carrier. In other embodiments, thecompositions will comprise a dual-selective PDE inhibitor (e.g., a PDEIII/IV inhibitor such as zardaverine). The present invention alsoprovides methods of using these compositions.

Phosphodiesterase inhibitors (PDE inhibitors) are agents which can blockthe breakdown of cAMP and cGMP in the tissue. PDE inhibitors includenon-specific PDE inhibitors and specific PDE inhibitors. A non-specificPDE inhibitor inhibits more than one type of phosphodiesterase, while aspecific PDE inhibitor inhibits only one type of phosphodiesterase withlittle, if any, effect on any other type of phosphodiesterase. Specificinhibitors of five cyclic nucleotide PDE isozyme families have beencharacterized: 8-methoxymethyl-IBMX (isobutyl methylxanthine) orvinpocetine (Ca²⁺, calmodulin-dependent PDE type I);EHNA(erythro-9-(2-hydroxy-3-nonyl)adenine HCl) (cGMP-stimulated PDE typeII); milrinone (cGMP-inhibited PDE type III); rolipram (cAMP-specificPDE type IV); and zaprinast and DMPPO (1,3dimethyl-6-(2-propoxy-5-methanesulphonylamidophenyl)-pyrazolo[3,4-d]pyrimidin-4-(5H)-one)(cGMP-specific PDE type V). Current knowledge suggests that there are atleast nine classes of PDE isozymes with type 9A having been recentlydiscovered (see, Fisher, et al., J. Biol. Chem. 273(25):15559-15564(1998)). Agents which are non-specific inhibitors of PDEs include, forexample, IBMX, theophylline, aminophylline, theobromine, dyphyllinecaffeine, etc. (see, Vemulapalli, et al., J Cardiovasc. Pharmacol28(6):862-9 (1996)).

Preferably, the compositions for treating anorectal disorders containone or more compounds selected from the classes of PDE II, PDE IV andPDE V inhibitors, or a dual PDE III/V inhibitor in a formulationsuitable for local treatment. Members of each of these classes can beadvantageously combined with a second agent selected from the group ofβ-adrenergic receptor agonists, preferably a β₂- or β₃-adrenergicreceptor agonists, α₁-adrenergic antagonists, L-type Ca²⁺ channelblockers, estrogens, ATP-sensitive K⁺ channel activators, sympatheticnerve terminal destroyers, adenosine receptor antagonists,methylxanthines, or smooth muscle relaxants. Preferred members from eachclass of additional agent are those which have been described above foruse with NO donors.

In embodiments comprising a second active agent with a PDE, a secondagent is preferably a K⁺ ATP channel opener, an adenosine receptorantagonist, or a β2-adrenergic receptor agonist. In yet furtherembodiments, a preferred second agent is a compound selected from thegroup consisting of theophylline, dyphylline, minoxidil, diazoxide,terbutaline, and salbutamol.

β-Adrenergic Receptor Agonist Compositions

In another aspect, the present invention provides pharmaceuticalcompositions for the treatment of anorectal disorders comprising aβ-adrenergic receptor agonist, preferably a β₂- or β₃-adrenergicreceptor agonist, either alone or in combination with another agentselected from cAMP-hydrolyzing PDE inhibitors (e.g., a PDE IVinhibitor), nonspecific PDE inhibitors, α₁-adrenergic antagonists,estrogens, L-type Ca²⁺ channel blockers, ATP-sensitive-K⁺ channelactivators, or smooth muscle relaxants, and a pharmaceuticallyacceptable carrier. The present invention further provides methods ofusing those compositions.

In this aspect of the invention, the β-adrenergic receptor agonist canbe essentially any of the β-adrenergic receptor agonists provided abovefor use in combination with NO donors. Preferably, the β-adrenergicagonist, is a β₂- or β₃-adrenergic receptor agonist. Particularlypreferred β-adrenergic agonists are those described in Bristol, et al.,ANNUAL REPORTS IN MEDICINAL CHEMISTRY, VOL. 33, Chap. 19, pp 193-202,Academic Press (1998) or are selected from salbutamol, terbutaline,procaterol, clenbuterol, isoproterenol, zinterol, BRL 37344, CL316243,CGP-12177A, GS 332, L-757793, L-760087, L-764646, and L-766892.

Terbutaline and salbutamol (albuterol) are β2-adrenergic agonistscommonly used for the long-term treatment of obstructive airway diseasesand acute bronchospasm in asthma. Beta-adrenergic agents, like VIP,potently relax smooth muscle, including IAS smooth muscle by raisingintracellular cyclic AMP levels (Parks et al., Gut 10(8): 674-7 (1969);Chakder, S. et al., Amer J Physiol. 264 (1 pt 1):G7-12, (1993); Chakder,S. et al., Amer J Physiol. 264 (4 pt 1): G702-7, (1993); O'Kelly, T. J.et al., Gut 34(5): 689-93, (1993)); O'Kelly, T. J. et al., Br J Surg80(10): 133741, (1993)). Cyclic AMP induces smooth muscle relaxationthrough phosphorylation of smooth muscle regulatory proteins (e.g.,myosin light chain kinase) and by decreasing intracellular calciumconcentrations (e.g., via K⁺-ATP channel activation). Terbutaline andsalbutamol have weaker cardiovascular effects than non-specificβ-receptor agonists, e.g., isoproterenol, because they do not stimulatecardiac β₁-adrenergic receptors at therapeutic doses. They are commonlyadministered by inhalation (i.e., topically). Tolerance is a potentialdownside effect of β₂-adrenergic agonists. Long-term systemicadministration of β-adrenergic agonists leads to down-regulation of βreceptors in some tissues and decreased pharmacological responses, andhas been demonstrated in patients with asthma¹.¹Goodman & Gilman's “The Pharmacological Basis of Therapeutics” 9thedition. Chapter 10, Catecholamines, Sympathomimetic Drugs andAdrenergic Receptor Antagonists. Brian B. Hoffman and Robert J.Lefkowitz, 1996.

In one group of embodiments, the compositions comprise forskolin.Forskoline directly activates adenyl cyclase avoiding tolerance.

In one group of embodiments, the composition contains a suitableβ-adrenergic receptor agonist and a pharmaceutically acceptable carrier,preferably one formulated for local delivery to the site of theanorectal disease or disorder.

In another group of embodiments, the composition contains another agentselected from cAMP-hydrolyzing PDE inhibitors (e.g., a PDE IVinhibitor), nonspecific PDE inhibitors, α₁-adrenergic antagonists,adenosine receptor antagonists including methyl xanthines, estrogens,L-type Ca²⁺ channel blockers, ATP-sensitive K⁺ channel activators orsmooth muscle relaxants.

In one preferred group of embodiments, the agent is a cAMP-hydrolyzingPDE inhibitor, more preferably a phosphodiesterase type IV inhibitor.Preferred phosphodiesterase type IV (also referred to as PDE IV andPDE4) inhibitors are described in, for example, Bristol, et al., AnnualReports in Medicinal Chemistry, Vol. 33, Chap. 10, pp 91-109, AcademicPress (1998). Most preferably, the PDE IV inhibitor is rolipram, Ro20-1724 or Etazolate.

In another group of preferred embodiments, the agent is a nonspecificPDE inhibitor such as, for example, IBMX, aminophylline, theophylline,pentoxifylline, theobromine, dyphylline, lisophylline and papaverine.

In yet another group of preferred embodiments, the agent is anα₁-adrenergic antagonist. Suitable α₁-adrenergic receptor antagonists(e.g. prazosin, doxazosin, phentolamine, tolazoline, and the like) aredescribed in Goodman & Gilman's THE PHARMACOLOGICAL BASIS OFTHERAPEUTICS, ninth edition, ed. J G Hardman, et al., McGraw-Hill(1996). Preferred agents for use in these compositions are selected fromprazosin, doxazosin, phentolamine, tolazoline and their derivatives.

In still other preferred embodiments, the β-adrenergic receptor agonistis combined with an type Ca²⁺ channel blocker, such as, for example,nifedipine, nimodipine, felopidine, nicardipine, isradipine, amlodipine,diltiazem, mentol, pinavarium bromide (a gastrointestinal tractselective calcium channel blocker; Awad R A et al., Acta Gastroent.Latinoamer. 27:247-251, 1997) and verapamil.

In yet other preferred embodiments, the β-adrenergic receptor agonist iscombined with an ATP-sensitive K⁺ channel activator. Preferred agentswithin this group are the same as those that have been provided abovefor use with NO donors.

Additional compositions are those in which a β-adrenergic receptoragonist is combined with an estrogen or estrogen like compound, or witha smooth muscle relaxant. Suitable compounds within each of theseclasses have been described above for use with NO donors.

In embodiments comprising a second active agent with a β₂-adrenergicreceptor agonist, a second agent is preferably a K⁺ ATP channel openeror an adenosine receptor antagonist. In yet further embodiments, apreferred second agent is a compound selected from the group consistingof theophylline, dyphylline, minoxidil, and diazoxide.

Potassium Channel Activator Compositions

In yet another aspect, the present invention provides compositions forthe treatment of anorectal disorders comprising an ATP-sensitive K⁺channel activator, either alone or in combination with another agentselected from cAMP-dependent protein kinase activators, estrogens,α₁-adrenergic antagonists, L-type Ca²⁺ channel blockers, sympatheticnerve terminal destroyers, or smooth muscle relaxants, and apharmaceutically acceptable carrier. The present invention furtherprovides methods of using those compositions.

In this aspect of the invention, the selected combinations are made fromthe components described in detail above for the NO donor compositions.Additional description of ATP-sensitive potassium ion channel activatorscan be found in, for example, Bristol, et al., ANNUAL REPORTS INMEDICINAL CHEMISTRY, VOL. 29, Chap. 8, pp 73-82, Academic Press (1991).In preferred embodiments the potassium ion channel activator isdiazoxide, minoxidil, PCO 400, pinocidil, levcromokalin, or cromokalim.

In some embodiments, the composition comprises an additional agent whichis a cAMP-dependent protein kinase activator, an estrogen or estrogenlike compound, an α₁-adrenergic antagonist, an L-type Ca²⁺ channelblocker, a sympathetic nerve terminal destroyer, or a smooth musclerelaxant. Preferably, the cAMP-dependent protein kinase activator is acAMP mimetic or a dual cGMP/cAMP-dependent protein kinase activator.More preferably, the cAMP mimetic is 8-bromo-cAMP, dibutyryl-cAMP,Rp-cAMPS, or Sp-cAMPS, and the dual activator is selected fromSp-8-pCPT-cGMPS, Sp-8-bromo-cGMPS and 8-CPT-cAMP.

In one group of embodiments, an α₁-adrenergic antagonist is combinedwith an ATP-sensitive potassium ion channel activator. Preferably, theα₁-adrenergic antagonist is prazosin, phentolamine or tolazoline.

In another group of embodiments, an L-type Ca²⁺ channel blocker iscombined with an ATP-sensitive potassium ion channel activator.Preferably, the L-type Ca²⁺ channel blocker is nifedipine, nimodipine,felopidine, nicardipine, isradipine, amlodipine, diltiazem, menthol,pinavarium bromide (a gastrointestinal tract selective calcium channelblocker; Awad R A et al., Acta Gastroent. Latinoamer. 27:247-251, 1997)or verapamil.

Diazoxide and minoxidil have been used for the treatment ofhypertension. These drugs are vasodilators that hyperpolarize arterialsmooth muscle cells by activating ATP-sensitive K⁺ channels (Meisheri etal., J Pharmacol Exp Ther 245(3): 751-60 (1988); Standen et al., Science245: 177-80 (1989)). Membrane hyperpolarization inactivatesvoltage-gated calcium channels, reduces intracellular calciumconcentrations, and causes muscle relaxation. ATP released by NANC nervestimulation probably relaxes the IAS through this mechanism (Brookes JGastroenterol Heaptol 8(6): 590-603 (1993); Rae et al., J Physiol(London) 493 (Pt 2): 517-27 (1996)). Baird and Muir (Baird et al., Br JPharmacol 100(2)329-35 (1990)) demonstrated that cromakalim, a K⁺-ATPchannel opener, inhibited spike discharge, hyperpolarized the membraneand relaxed the guinea pig IAS. In our studies, diazoxide and minoxidilrelaxed the rat IAS in vivo. The adverse effects of these drugs arepredictable and can be divided into three major categories: 1) fluid andsalt retention, 2) cardiovascular effects, and 3) hypertrichosis.Topical minoxidil, inspired by the hypertrichosis side effect, ismarketed for stimulating hair growth. This product has an excellentsafety record and is now sold over the counter.

In still another group of embodiments, a smooth muscle relaxant iscombined with an ATP-sensitive potassium ion channel activator.Preferably, the smooth muscle relaxant is hydralazine, papaverine,tiropramide, cyclandelate, isoxsuprine or nylidrin.

In embodiments comprising a second active agent with a K⁺ ATP channelopener, a second agent is preferably a K⁺ ATP channel opener, aβ₂-adrenergic receptor agonist, or an adenosine receptor antagonist. Inyet further embodiments, a preferred second agent is a compound selectedfrom the group consisting of theophylline, dyphylline, terbutaline, andsalbutamol.

α₁-Adrenergic Antagonist Compositions

In still another aspect, the present invention provides compositions forthe treatment of anorectal disorders comprising an α₁-adrenergicantagonist, either alone or in combination with another agent selectedfrom cAMP-hydrolyzing PDE inhibitors (preferably a PDE IV inhibitor),estrogens, sympathetic nerve terminal destroyers, or smooth musclerelaxants, and a pharmaceutically acceptable carrier. The presentinvention further provides methods of using those compositions.

α₁-Adrenergic antagonists which are useful in this aspect of theinvention have been described above and can be found in, for example,Goodman & Gilman's THE PHARMACOLOGICAL BASIS OF THERAPEUTICS, ninthedition, ed. J G Hardman, et al., McGraw-Hill (1996). Preferredα₁-adrenergic antagonists are prazosin, phentolamine and tolazoline.

For those embodiments in which an α₁-adrenergic antagonist is combinedwith a cAMP-hydrolyzing PDE inhibitor (preferably a PDE IV inhibitor),an estrogen or estrogen like compound, a sympathetic nerve terminaldestroyer, or a smooth muscle relaxant, the preferred members of eachclass are those which have been described above for use with NO donors.

In embodiments comprising a second active agent with a α₁-adrenergicantagonist, a second agent is preferably a K⁺ ATP channel opener, aβ₂-adrenergic receptor agonist or an adenosine receptor antagonist. Inyet further embodiments, a preferred second agent is a compound selectedfrom the group consisting of theophylline, dyphylline, minoxidil,diazoxide, terbutaline, and salbutamol.

Cyclic Nucleotide-Dependent Protein Kinase Activator Compositions

In another aspect, the present invention provides pharmaceuticalcompositions for the treatment of anorectal disorders comprising cyclicnucleotide-dependent protein kinase activators, either alone or incombination with another agent. Methods for the use of thesecompositions are also provided. In one group of embodiments,cGMP-dependent protein kinase activators are used alone. In anothergroup of embodiments, nonspecific cyclic nucleotide-dependent proteinkinase activators are used alone. In yet another group of embodiments,nonspecific cyclic nucleotide-dependent protein kinase activators areused in combination with smooth muscle relaxants. In still another groupof embodiments, cAMP-dependent protein kinase activators are provided incombination with L-type Ca²⁺ channel blockers.

In embodiments comprising a second active agent with the protein kinaseactivator, a second agent is preferably a K⁺ ATP channel opener, aβ₂-adrenergic receptor agonist or an adenosine receptor antagonist. Inyet further embodiments, a preferred second agent is a compound selectedfrom the group consisting of theophylline, dyphylline, terbutaline,minoxidil, diazoxide and salbutamol.

In each instance, preferred members of the recited classes of compoundsare those that have been described above for use alone or in othercombinations.

Estrogen and Estrogen Mimetic Compositions

In another aspect, the present invention provides pharmaceuticalcompositions for the treatment of anorectal disorders comprisingestrogen or an estrogen mimetic, either alone or in combination withanother agent from any of the classes of agents described above.Estrogen-like compounds include but are not limited to17-beta-estrodiol, estrone, mestranol, estradiol valerate, estrodioldypionate, ethinyl estrodil, quinestrol, estrone sulfate, phytoestrogenssuch as flavones, isoflavones (e.g. genistein), resveratrol, coumestanderivatives, other synthetic estrogenic compounds including pesticides(e.g. p,p′-DDT), plasticizers (e.g. bisphenol A), and a variety of otherindustrial chemicals (e.g. polychlorinated biphenyls) (Goodman &Gilman's THE PHARMACOLOGICAL BASIS OF THERAPEUTICS, ninth edition, ed. JG Hardman, et al., McGraw-Hill (1996). Preferred agents are selectedfrom those described with reference to the compositions of single agentsor combinations above. Methods for the use of these compositions arealso provided.

In embodiments comprising a second active agent with the estrogenicagent, a second agent is preferably a K⁺ ATP channel opener, aβ₂-adrenergic receptor agonist or an adenosine receptor antagonist. Inyet further embodiments, a preferred second agent is a compound selectedfrom the group consisting of theophylline, dyphylline, terbutaline,minoxidil, diazoxide and salbutamol.

Sympathetic Nerve Terminal Destroyer Compositions

In another aspect, the present invention provides pharmaceuticalcompositions for the treatment of anorectal disorders comprising asympathetic nerve terminal destroyer, either alone or in combinationwith another agent from any of the classes of agents described above.The sympathetic nerve terminal destroyer compounds include but are notlimited to 6-hydroxydopamine and its analogs See, Goodman & Gilman's THEPHARMACOLOGICAL BASIS OF THERAPEUTICS, ninth edition, ed. J G Hardman,et al., McGraw-Hill (1996). Preferred agents are selected from thosedescribed with reference to the compositions of single agents orcombinations above. Methods for the use of these compositions are alsoprovided.

Adenosine Receptor Antagonists/Methylxanthines

In another aspect, the present invention provides pharmaceuticalcompositions for the treatment of anorectal disorders comprising aadenosine receptor antagonist, either alone or in combination withanother agent from any of the classes of agents described above.Examples of adenosine receptor antagonists include theophylline anddyphylline. See, Goodman & Gilman's THE PHARMACOLOGICAL BASIS OFTHERAPEUTICS, ninth edition, ed. J G Hardman, et al., McGraw-Hill(1996). Preferred agents are selected from those described withreference to the compositions of single agents or combinations above.Methods for the use of these compositions are also provided.

Theophylline, a plant-derived methylxanthine, has been used for thetreatment of bronchial asthma for decades. Theophylline relaxes smoothmuscle, notably bronchial muscle, that has been contractedexperimentally with a spasmogen, or clinically in asthma. We found thattheophylline relaxed the rat IAS when instilled into the distal analcanal. Proposed mechanisms of methylxanthine-induced physiologic andpharmacological effects include: 1) inhibition of phosphodiesterases,thereby increasing intracellular cyclic AMP, 2) direct effects onintracellular calcium concentration, 3) indirect effects onintracellular calcium concentrations via cell membranehyperpolarization, 4) uncoupling of intracellular calcium increases withmuscle contractile elements, and 5) antagonism of adenosine receptors.Adenosine receptor antagonism is thought to be the most important factorresponsible for most of the pharmacological effects of methylxanthinesin therapeutically administered doses².² Goodman & Gilman's “The Pharmacological Basis of Therapeutics” 9thedition. Chapter 28, Drugs Used in the Treatment of Asthma. William E.Serafin, 1996.

We have found the related compound, dyphylline, to also reduce IASP intests. Dyphylline is not metabolized by the liver and is excretedunchanged by the kidneys, therefore its pharmacokinetics and plasmalevels are independent of factors that effect liver enzymes such assmoking, age, congestive heart failure, or the use of other drugs thataffect liver function.

In embodiments comprising a second active agent with the adenosinereceptor antagonist, a second agent is preferably a K⁺ ATP channelopener or a β₂-adrenergic receptor agonist. In yet further embodiments,a preferred second agent is a compound selected from the groupconsisting of terbutaline, minoxidil, diazoxide and salbutamol.

Formulations for the Treatment of Anorectal Disorders

Many of the individual components of the compositions above have beendescribed for use in a variety of disease states. However, certainclasses and combinations of classes have now been found to be useful forthe treatment of anorectal diseases and can be provided in formulationsbest suited for delivery to an appropriate anal area. Preferredformulations are those in which the components are combined in a topicalformulation for local application to the external or internal anus, theexternal or internal anal sphincter, anal sphincter muscle, the externalor internal anal canal and the lower rectum above the anal canal.

Accordingly, each of the compositions provided above will typically bepresented in an appropriate pharmaceutical formulation comprising aneffective amount of the noted agents (e.g., NO donors, β₂- orβ₃-adrenergic receptor agonists, cAMP-hydrolyzing PDE inhibitors,nonspecific PDE inhibitors, α₁-adrenergic antagonists, L-type Ca²⁺channel blockers, ATP-sensitive K⁺ channel activators, adenosinereceptor antagonists, and the like).

One of skill in the art will appreciate that suitable formulations aredependent on the form of delivery to be employed, and all such forms arecontemplated by the present invention. Additionally, in someembodiments, combinations of agents are employed in a singleformulation, while in other embodiments, agents are formulatedseparately, but administered in combination, or sequentially. In thediscussion below, compositions of single agents will be understood toalso include compositions of two or more agents. Still further,different formulations can be used for those embodiments in which agentsare administered separately or sequentially, by different routes ofadministration.

Topical Compositions

In view of the above, the present invention provides topicalcompositions useful for treating anorectal disorders (including thoserelated to hypertonicity and/or spasm of the internal anal sphinctermuscle, e.g. hemorrhoidal pain) and for treating spasms of the mammal,including humans, which comprise an effective amount of an agent thatreduces the contraction of anal sphincter muscle or maintains a reducedcontraction of the anal sphincter muscle, and a pharmaceuticallyacceptable carrier. In one embodiment, the agent is an ATP-sensitivepotassium channel opener. In another embodiment, the agent is aphosphodiesterase inhibitor, a cyclic nucleotide mimic, β-adrenergicagonist, an estrogen or estrogen like compound, an α₁-adrenergicantagonist or a potassium channel opener.

In related embodiments, the present invention provides topicalpharmaceutical compositions in unit dosage form comprising per unitdosage an amount of the agent or combination provided above, which iseffective for treating an anal disorder in a subject in need of suchtreatment. Typically the agents are in combination with apharmaceutically acceptable carrier. Such compositions are useful intreating or reducing pain associated with anal disorders, such ashemorrhoidal pain, and for treating spasms and/or hypertonicity of thesphincters, including the internal anal sphincter, lower esophagealsphincter, pyloric sphincter, sphincter of Oddi, and the ileocolicsphincter. The topical composition is also useful in treating conditionsresulting from spasms and/or hypertonicity of sphincters of theanorectal region including anal fissure, post-operative rectal pain,hypertrophic pyloric stenosis, and pancreatitis, as well as conditionsresulting from general spasm of the muscles of the GI tract includingZenkers diverticulum, achalasia, esophageal spasm (nutcrackeresophagus), irritable bowel disease, and Hirshprungs disease (bowelobstruction). In addition, the topical compositions are useful forrelaxing the anal sphincter, reducing anal sphincter pressure ormaintaining reduced anal sphincter pressure and reducing pain anddiscomfort before, during and after examinations of the anus, rectum andlower gastrointestinal system, insertion of instruments, and proceduressuch as colonoscopy, cystoscopy and surgery.

Dosage Forms

Topical Administration

Dosage forms for the topical administration of the anal sphincterrelaxing agents of this invention include powders, sprays, ointments,pastes, creams, lotions, gels, solutions, patches, suppositories andliposomal preparations. The dosage forms may be formulated withmucoadhesive polymers for sustained release of the active compound(s) atthe anal mucosa. The active compound may be mixed under sterileconditions with a pharmaceutically acceptable carrier, and with anypreservatives, buffers, or propellants, which may be required. Topicalpreparations can be prepared by combining the anal sphincter relaxingagent with conventional pharmaceutical diluents-and-carriers commonlyused in topical dry, liquid, cream and aerosol formulations. Ointmentand creams may, for example, be formulated with an aqueous or oily basewith the addition of suitable thickening and/or gelling agents. Suchbases may include water and/or an oil such as liquid paraffin or avegetable oil such as peanut oil or castor oil. Thickening agents whichmay be used according to the nature of the base include soft paraffin,aluminum stearate, cetostearyl alcohol, propylene glycol, polyethyleneglycols, woolfat, hydrogenated lanolin, beeswax, and the like. Lotionsmay be formulated with an aqueous or oily base and, in general, alsoinclude one or more of the following: stabilizing agents, emulsifyingagents, dispersing agents, suspending agents, thickening agents,coloring agents, perfumes, and the like. Powders may be formed with theaid of any suitable powder base, e.g., talc, lactose, starch, and thelike. Drops may be formulated with an aqueous base or non-aqueous basealso comprising one or more dispersing agents, suspending agents,solubilizing agents, and the like.

The ointments, pastes, creams and gels also may contain excipients, suchas animal and vegetable fats, oils, waxes, paraffins, starch,tragacanth, cellulose derivatives, polyethylene glycols, silicones,bentonites, silicic acid, talc and zinc oxide, or mixtures thereof.Powders and sprays also can contain excipients such as lactose, talc,silicic acid, aluminum hydroxide, calcium silicates and polyamidepowder, or mixtures of these substances. Sprays can additionally containcustomary propellants, such as chlorofluorohydrocarbons and volatileunsubstituted hydrocarbons, such as butane and propane.

Representative compositions include topical compositions comprising oneor more of the following first pharmacologic agents: an NO donor,phosphodiesterase inhibitor, cyclic nucleotide mimetic, β-adrenergicagonist, L-type calcium channel blocker, α-adrenergic antagonist,ATP-sensitive potassium channel activator, sympathetic nerve terminaldestroyer, estrogen or estrogen-like compound or botulinum toxin incombination with a pharmaceutically acceptable carrier and at least oneof the following second pharmacologic agents: a local anesthetic (e.g.,lidocaine, prilocaine, etc.), local anti-inflammatory agent (e.g.,naproxen, pramoxicam, etc.), corticosteroid (e.g. cortisone,hydrocortisone, etc.), anti-itch agent (e.g., loperamidediphylenoxalate, etc.), an agent that interferes with the activation ofperipheral sensory neurons, including divalent and trivalent metal ions(e.g., manganese, calcium, strontium, nickel, lanthanum, cerium, zinc,etc.), analgesic-agents, yeast-based product (e.g., lyophilized yeast,yeast-extract, etc.), growth-promoting and/or wound healing-promotingagent known to promote re-epithelialization (e.g., platelet-derivedgrowth factor PDGF, interleukin-11 (IL-11) etc.), anti-microbial agent(e.g., neosporin, polymyxin B sulfate, bacitracin zinc, etc.),mucoadhesive agent (e.g., cellulose derivatives, etc.), cytoprotectantagent (e.g., colloidal bismuth, misoprostol, etc., with the exception ofsucralfate) as defined in GOODMAN & GILMAN'S THE PHARMACOLOGICAL BASISOF THERAPEUTICS, supra, an agent that promotes local tissue sclerosis(e.g., alum, etc.), or menthol. The first pharmacologic agent istypically present in the composition in unit dosage form effective fortreatment of a first medical condition(s), such as an anal disease orpain associated with an anal disease. The second pharmacologic agent istypically present in the composition in unit dosage form effective fortreatment of a second medical condition(s), or a condition(s),symptom(s) or effect(s) associated with or resulting from the firstmedical condition(s).

In one aspect, the invention provides compositions for treatinganorectal disorders which comprise an active agent and apharmaceutically acceptable carrier. The active agent comprises an agentthat stimulates or causes an increase of either CGMP or cAMP throughactivation of guanylyl or adenylyl cyclase, respectively, a cyclicnucleotide mimetic, PDE inhibitor, α-adrenergic receptor antagonist, orβ-adrenergic receptor agonist, or potassium channel opener. In oneaspect, the active agent is present in compositions of the invention inan amount of from about 0.001% to about 15% by weight of thecomposition. In another aspect, the active agent is present in an amountof from about 0.01% to about 7.5% by weight, more preferably from about0.05% to about 2% by weight of the composition.

For example, in one group of embodiments, the invention providescompositions for treating anorectal disorders comprising apharmaceutically acceptable carrier and an amount of from about 0.001%to about 15% sildenafil by weight. In another aspect, compositionscomprising a pharmaceutically acceptable carrier and an amount of fromabout 0.01% to about 7.5% or from about 0.05% to about 2% sildenafil byweight are provided.

The topical pharmaceutical compositions can also include one or morepreservatives or bacteriostatic agents, e.g., methyl hydroxybenzoate,propyl hydroxybenzoate, chlorocresol, benzalkonium chlorides, and thelike. The topical pharmaceutical compositions also can contain otheractive ingredients such as antimicrobial agents, particularlyantibiotics, anesthetics, analgesics, and antipruritic agents.

One example of a topical formulation includes 75% (w/w) white petrolatumUSP, 4% (w/w) paraffin wax USP/NF, lanolin 14% (w/w), 2% sorbitansesquioleate NF, 4% propylene glycol USP, and 1% anal sphincter relaxingagent.

The dosage of a specific anal sphincter relaxing agent depends upon manyfactors that are well known to those skilled in the art, for example,the particular agent; the condition being treated; the age, weight, andclinical condition of the recipient patient; and the experience andjudgment of the clinician or practitioner administering the therapy. Aneffective amount of the compound is that which provides eithersubjective relief of symptoms or an objectively identifiable improvementas noted by the clinician or other qualified observer. The dosing rangevaries with the compound used, the route of administration and thepotency of the particular compound.

Transmucosal (i.e., sublingual, rectal, colonic, pulmonary, buccal andvaginal) drug delivery provides for an efficient entry of activesubstances to systemic circulation and reduces immediate metabolism bythe liver and intestinal wall flora (See Chien Y. W., NOVEL DRUGDELIVERY SYSTEMS, Chapter 4 “Mucosal Drug Delivery,” Marcel Dekker, Inc.(1992). Transmucosal drug dosage forms (e.g. tablet, suppository,ointment, gel, pessary, membrane, and powder) are typically held incontact with the mucosal membrane and disintegrate and/or dissolverapidly to allow immediate local and systemic absorption. Theseformulations are used along with the anti-inflammatory agents of thepresent invention for reducing or eliminating inflammation oftransmucosal membranes.

In order to enhance transmucosal absorption efficiency andbioavailability of the active agents, selected mucosal adhesive polymersor dosages can be employed. For example, a selected potassium channelopener, e.g. minoxidil can be formulated in a liquid suppository inwhich mucoadhesive polymers such as polyvinylpyrrolidone (PVP, BASF,Germany), polycarbophil (Goodrich, USA), or sodium alginate (HayashiPure Chemicals, Tokyo, Japan), etc. are incorporated. This type ofliquid suppository has a gelation temperature between 30 to 36° C. andhas a mucoadhesive force of 430 to 5800 dyne/cm. As a result, thesuppository remains as an easy to apply liquid at room temperature, gelsat physiological temperature and remain adhered to the anal mucosalmembrane for a sustained period of time (Rye J M et al., Journal ofControlled Release, 59:163-172. 1999; Chem Pharm Bull, 46 (2):309-313,1998; J Pharm Sci, 81(11):1119-1125, 1992; Chem Pharm Bull,37(3):766-770, 1989; J Pharmacobiodyn, 9(6):526-531, 1986; J Pharm Sci.84(1):15-20, 1995).

Preferred formulations are either as solutions or semi-solidpreparations (gel, ointment, suspension, lotion, cream, etc.). Suitableexcipients, depending on the agent, include petrolatum, lanolin,methylcellulose, sodium carboxymethylcellulose, hydroxpropylcellulose,sodium alginate, carbomers, glycerin, glycols, oils, glycerol,benzoates, parabens and surfactants. It will be apparent to those ofskill in the art that the solubility of a particular compound will, inpart, determine how the compound is formulated. An aqueous gelformulation will is suitable for soluble compounds. Where a compound isinsoluble at the concentrations required for activity, a cream orointment preparation will typically be preferable. In this case, oilphase, aqueous/organic phase and surfactant may be required to preparethe formulations. Thus, based on the solubility and excipient-activeinteraction information, the dosage forms can be designed and excipientscan be chosen to formulate the prototype preparations. Particularlypreferred preparations include those in a suppository or sustainedrelease format.

Sustained or Controlled Delivery Formulations

In yet other embodiments, the invention provides topical sustained andprolonged release pharmaceutical compositions comprising one or moreanal sphincter relaxant, including nitric oxide donors (such asnitroglycerin, isosorbide dinitrate, and L-arginine) or thepharmacological agents described above and a pharmaceutically acceptablecarrier, to treat anorectal disorders. The compositions are useful inthe treatment of such disorders as reducing anal sphincter pressure,maintaining reduced anal sphincter pressure, and in controlling andreducing pain associated with such disorders. Such compositions maycomprise a unit dosage of one or more active agents (e.g., nitric oxidedonor) which is effective in treating anal disorders and in controllingand alleviating pain associated therewith. Preferably, the compositionsare administered in unit dosage form to a subject in need of suchtreatment. In other embodiments, the compositions contain an NO donor inan amount which is less than an effective amount when used alone, butwhich is effective when used in combination with a second agent whichmodulates levels of cAMP or cGMP in a subject. Topical sustained andprolonged release compositions are typically variants which include 1)an absorbent in a hydrophilic base; 2) an absorbent in a hydrophobicbase; and 3) coated beads containing an absorbent matrix dispersed in asuitable vehicle. Also provided are methods of treating anal or GI tractdisorders comprising topically administering an effective amount of suchcompositions (e.g., in unit dosage form) to the appropriate anal area ofthe subject in need of such treatment.

Such hydrophilic compositions and preparations of the invention comprisea nitric oxide donor (or other suitable agent or combination of agents)and a polymer, such as cellulose (methyl cellulose, ethyl cellulose,hydroxy propyl cellulose, etc.), higher molecular weight polyethyleneglycol, methacrylic-acrylic acid emulsion, hydrogel, carbopol, ethylvinyl acetate copolymer, or polyester, etc., to bind the nitric oxidedonor to the polymer. The nitric oxide donor-polymer matrix oragent-polymer matrix is then dispersed in a hydrophilic vehicle to forma semi-solid. After administration of such hydrophilic composition intothe appropriate anal area, such as the anal canal or anal sphincter, thewater in the semi-solid preparation is adsorbed and the polymer matrixwith the active ingredient—the nitric oxide donor or other agent—remainsas a coating in the anal region or area to which it has been applied.The nitric oxide donor is then slowly released from this coating.

Hydrophobic compositions and preparations of the inventions employsimilar polymers as used in the hydrophilic preparations, but thepolymer/nitric oxide donor matrix is dispersed into a vehicle, such aplastibase, in the hydrophobic compositions and preparations. Plastibaseis a mineral oil base that only partially dissolves the nitric oxidedonor. The semi-solid composition forms a thin coating on the analregion to which the composition has been applied (such as the anal canalor anal sphincter area) and slowly releases the active. The prolongedaction is controlled principally by the solubility of the activeingredient (nitric oxide donor) in the vehicle.

The present invention also provides coated beads which are produced byfirst absorbing the nitric oxide donor or other agent or combination ofagents on a cellulosic material blended with polyethylene glycol,filler, binder and other excipients. The resulting matrix is thenextruded and spheronized (e.g., the process of making into spheres) tocreate small beads. The beads are then coated to an appropriatethickness with one or more of a suitable material, such as amethacrylic-acrylic polymer, polyurethane, ethyl vinyl acetatecopolymer, polyester, silastic, etc. The coating on the beads acts as arate controlling membrane which regulates the release of the agent fromthe core beads.

Oral Formulations

In still another embodiment, the invention provides pharmaceuticalcompositions suitable for oral administration which are provided in unitdosage form comprising per unit dosage a phosphodiesterase inhibitor,cyclic nucleotide mimetic, or β-adrenergic agonist, and apharmaceutically acceptable carrier. Such compositions are useful fortreating anorectal disorders, including those disorders and conditionsprovided above.

For delivery to the buccal membranes, typically an oral formulation,such as a lozenge, tablet, or capsule is used. The method of manufactureof these formulations are known in the art, including but not limitedto, the addition of a pharmacological agent to a pre-manufacturedtablet; cold compression of an inert filler, a binder, and either apharmacological agent or a substance containing the agent (as describedin U.S. Pat. No. 4,806,356); and encapsulation. Another oral formulationis one that can be applied with an adhesive, such as the cellulosederivative, hydroxypropyl cellulose, to the oral mucosa, for example asdescribed in U.S. Pat. No. 4,940,587. This buccal adhesive formulation,when applied to the buccal mucosa, allows for controlled release of thepharmacological agent into the mouth and through the buccal mucosa. Theanti-inflammatory agents of the present invention can be incorporatedinto these formulations as well.

Aerosol Formulations

For delivery to the nasal or bronchial membranes, typically an aerosolformulation is employed. The term “aerosol” includes any gas-bornesuspended phase of the pharmacological agent which is capable of beinginhaled into the bronchioles or nasal passages. Specifically, aerosolincludes a gas-borne suspension of droplets of the compounds of theinstant invention, as may be produced in a metered dose inhaler ornebulizer, or in a mist sprayer. Aerosol also includes a dry powdercomposition of a compound of the pharmacological agent suspended in airor other carrier gas, which may be delivered by insufflation from aninhaler device, for example. For solutions used in making aerosols, thepreferred range of concentration of the pharmacological agent is 0.1-100milligrams (mg)/milliliter (mL), more preferably 0.1-30 mg/mL, and mostpreferably, 1-10 mg/mL. Usually the solutions are buffered with aphysiologically compatible buffer such as phosphate or bicarbonate. Theusual pH range is 5 to 9, preferably 6.5 to 7.8, and more preferably 7.0to 7.6. Typically, sodium chloride is added to adjust the osmolarity tothe physiological range, preferably within 10% of isotonic. Formulationof such solutions for creating aerosol inhalants is discussed inRemington's Pharmaceutical Sciences, see also, Ganderton and Jones, DRUGDELIVERY TO THE RESPIRATORY TRACT, Ellis Horwood (1987); Gonda (1990)Critical Reviews in Therapeutic Drug Carrier Systems 6:273-313; andRaeburn et al., (1992) J Pharmacol Toxicol Methods 27:143-159.

Solutions of the pharmacological agent may be converted into aerosols byany of the known means routinely used for making aerosol inhalantpharmaceuticals. In general, such methods comprise pressurizing orproviding a means of pressurizing a container of the solution, usuallywith an inert carrier gas, and passing the pressurized gas through asmall orifice, thereby pulling droplets of the solution into the mouthand trachea of the animal to which the drug is to be administered.Typically, a mouthpiece is fitted to the outlet of the orifice tofacilitate delivery into the mouth and trachea.

Parenteral Formulations

In yet another embodiment, the invention provides pharmaceuticalcompositions suitable for parental administration which are provided inunit dosage form comprising per unit dosage a phosphodiesteraseinhibitor, cyclic nucleotide mimetic, or β-adrenergic agonist, and apharmaceutically acceptable carrier. Such compositions are useful fortreating anorectal disorders and conditions as described above.

Methods of Treating Anorectal Disorders

In another aspect, the present invention provides methods for treatinganorectal disorders which comprise administering to an appropriate analarea or affected anal tissue (e.g., external or internal anal tissue oranal canal) of a subject in need of such treatment an effective amountof any of the compositions provided above. By use of such methods of theinvention, anorectal hypertonicity and/or spasms are relieved, analsphincter pressure is reduced, reduced anal sphincter pressure ismaintained, and signs and symptoms associated with anorectal disorders,e.g. anal fissures, anal ulcers and hemorrhoids, and pain are improved.The methods described herein are also applicable to the treatment ofrecurrent anal diseases, and are also useful for relaxing the analsphincter and reducing pain during anorectal exams (in patients with andwithout disorders), particularly during procedures when instruments areinserted into the anus.

The present invention further provides methods of using the compositionsabove in combination with local anesthetic agents, for examplelidocaine, prilocaine, etc. Each of the compositions will typically bein a pharmaceutically acceptable dosage form as an effective treatmentfor a medical condition such as hemorrhoidal pain and for treatingspasms and/or hypertonicity of the sphincters including the internalanal sphincter, lower esophageal-sphincter, pyloric sphincter, sphincterof Oddi, and the ileocolic sphincter. These pharmaceutical preparationsare also useful in treating conditions resulting from spasms and/orhypertonicity of sphincters of the anorectal region including analfissure, post-operative rectal pain, hypertrophic pyloric stenosis, andpancreatitis, as well as conditions resulting from general spasm of themuscles of the GI tract including Zenkers diverticulum, achalasia,esophageal spasm (nutcracker esophagus), irritable bowel disease, andHirschsprung's disease (bowel obstruction). In another aspect, thepresent invention provides methods for treating anal disorders whichcomprise administering an effective amount of such composition alongwith a local anesthetic agent to a subject in need of such treatment.Such compositions can be administered orally, topically, orparenterally.

Similarly, the invention provides methods of using the compositionsabove in combinations with local anti-inflammatory agents, for example,naproxen, piroxicam, etc. in a pharmaceutically acceptable dosage formas an effective treatment for a medical condition such as hemorrhoidalpain and for treating hypertonicity and/or spasms of the sphinctersincluding the internal anal sphincter, lower esophageal sphincter,pyloric sphincter, sphincter of Oddi, and the ileocolic sphincter. Thesepharmaceutical preparations are also useful in treating conditionsresulting from spasms and/or hypertonicity of sphincters of theanorectal region including anal fissure, post-operative rectal pain,hypertrophic pyloric stenosis, and pancreatitis, as well as conditionsresulting from general spasm of the muscles of the GI tract includingZenkers diverticulum, achalasia, esophageal spasm (nutcrackeresophagus), irritable bowel disease, and Hirschsprung's disease (bowelobstruction). In another aspect, the present invention provides methodsfor treating anal disorders which comprise administering an effectiveamount of such composition along with a local anesthetic agent to asubject in need of such treatment. Such compositions can be administeredorally, topically, or parenterally.

Additional methods provided by the present invention are those in whichtwo or more agents selected from NO donors, phosphodiesterase type V(PDE V) inhibitor, a phosphodiesterase type II (PDE II) inhibitor, anonspecific PDE inhibitor, a dual-selective PDE inhibitor, aβ-adrenergic agonist, a cAMP-dependent protein kinase activator, anα₁-adrenergic antagonist, a superoxide anion (O₂ ⁻) scavenger, anATP-sensitive K⁺ channel activator, an estrogen or estrogen mimetic, asympathetic nerve terminal destroyer, an adenosine receptor antagonist,or a smooth muscle relaxant, are administered either in combination orsequentially to provide an enhanced therapeutic benefit. In particular,the use of an NO donor and a second agent from those provided above canprovide fewer and less severe side effects than equally effective dosesof NO donors, if used alone. More particularly, the use of an NO donorin combination with a second agent allows for decreased amounts of theNO donor to be used to achieve the same benefit relative to use alone,while extending the period of reduction of anal sphincter pressure, andprovides significantly reduced occurrence and duration of headaches.

EXAMPLES Example 1

This example illustrates the effect of cGMP mimetics, alone and incombination with a NO donor in a rat internal anal sphincter (IAS)relaxation model.

Male Sprague-Dawley rats (300-400 gm) were anesthetized with ketamine(90 mg/kg), xylazine (9 mg/kg) given intramuscularly and supplemented asneeded with ⅓^(rd) dose. Rats were gently restrained on their backs on aheated surgical table (Harvard Apparatus) for the duration of theexperiments. The diuretic effects of anesthesia was offset byrehydration with saline through an intraperitoneal implanted 24 gaugeangiocatheter (VWR, San Francisco, Calif.). The constriction/relaxationmeasurement assembly included a Millar catheter/transducer (1.67 mmdiameter.) connected to a Digi-Med Low Pressure Analyzer (Micro-Med)accurate for pressure measurements between −50 and 150 mmHg. The datawere integrated and converted to waveforms with the Digi-Med SystemIntegrator software. Blood pressure changes were monitored using anarterial catheter/transducer and a Digi-Med Blood Pressure Analyzer withthe DMSI software. Respiratory changes were monitored using a mercurystrain gauge/transducer, wrapped around the rib-cage of the rat, hookedup to a Digi-Med Analog Signal Analyzer along with the DMSI software.Drug delivery was accomplished through two Hamilton syringes with nodead space using PE 10 tubing adjacent to the catheter sensor. Drugs,typically were applied soon after stable baseline readings are recorded.Although unanesthetized restrained rats had been used in other studies,no differences have been observed in resting anal pressures afteranesthesia; therefore, these studies were carried out with anesthetizedrats to avoid undue distress to the animals.

Typical resting mean internal anal sphincter pressures (IASP) variedbetween 30 and 60 mmHg in this model. The Millar catheter sensor allowedfor accurate, isolated recordings of the IAS. FIG. 1 represents atypical waveform pattern for resting IASP in a rat under conditions of acontrol experiment. The first 10 minutes after treatment withnitroglycerin is shown in FIG. 2.

Using the same experimental protocol, the effect of a cGMP mimetic,dibutyryl-cGMP was studied. FIG. 3 shows that 20 μl of a 10% solution ofdibutyryl-cGMP in saline applied to the anal canal reduced the mean IASPby 45% over 2.5 hours following treatment. The average IASP over thelast hour prior to terminating the experiment had dropped 60%.

The IASP was still reduced 34% by the following morning indicating apotential long-term effect of the drug. A subsequent dose of 1%nitroglycerin dropped the IASP by 24% for 30 minutes and 71% for thefirst 10 minutes following treatment. After IASP returned topre-treatment levels, a further dose of dibutyryl-cGMP was administeredand found to lower IASP 15% over the ensuing 3 hours and 10 minutes.

These results support the effect of cGMP mimetics in relaxing analsphincter muscle tone, and more importantly, suggest a potential benefitof using a combination of NO donor and cGMP mimetic due the quick onsetof action of the NO donor and the more prolonged duration of relaxationproduced by the cGMP mimetics.

Example 2

This example illustrates the effect of phosphodiesterase inhibitors in arat internal anal sphincter relaxation model.

Using the same experimental protocol described above, an application of20 μL of a 5% zaprinast solution in 1-methyl-2-pyrrolidinone reducedmean IASP by 21% over 32 minutes compared with vehicle treatment alone.The effect of phosphodiesterase inhibitors could be further enhanced byminimal concentrations of NO donors, such as nitroglycerin that produceda quicker onset and sustained sphincter relaxation without headache andother adverse reactions observed with high dose of NO donors alone (seeFIG. 4).

Example 3

This example illustrates the effect of a potassium channel opener(minoxidil) in a rat internal anal sphincter constriction/relaxationmodel.

Following the same experimental protocol as described above, a single 20μl dose of a 4% solution of minoxidil in 62.5% propylene glycol resultedin a 64% reduction of the IASP over 2.5 hours following treatment. Thevehicle alone had little effect on IASP (see FIG. 5).

Example 4

This example illustrates the use of a variety of compositions of theinvention for the relaxation of the IAS.

In this example, male Sprague-Dawley rats (250-300 g each) from CharlesRiver were used. The rats were anesthetized intramuscularly withketamine (90 mg/kg) and xylazine (9 mg/kg) and kept warm on a heatedsurgical table. All internal anal sphincter pressures (IASP) weremeasured with Millar catheter/transducers (MPC-500 mikro-tip; MillarInstruments, Houston) on low pressure analyzers and blood pressureanalyzers and recorded by DMSI software provided by Micro-Med(Louisville). Rats were provided with saline i.p. for rehydration due tothe diuretic effects of the anesthesia and re-anesthetized as neededwith approximately ⅓ the original dosage. In most experiments, the IASPwas allowed to reach a stable baseline level prior to drug delivery.Drugs were delivered to the anal sphincter mainly via PE 20 tubingattached to the catheter(s) near the sensor(s) from 100 μl or 250 μlHamilton syringes either manually or by infusion with a programmableHarvard automatic infusion pump.

Example 5

This example illustrates the effect of repeated or prolonged dosing of anitric oxide donor (NTG) on the responsiveness of the rat IAS.

One issue with chronic or subchronic therapy with nitric oxide or nitricoxide donors such as NTG is the extent of any tachyphylaxis or toleranceto the relaxant effect of nitric oxide. Clinical studies have shown thatthe human cardiovascular system develops tolerance to nitric oxidedonors. We have found that in the rat model, cardiovascular tolerance,as measured in vivo by the mean-arterial-blood pressure, also developswith repeated dosing of NTG. At the biochemical level, using in vitroassays, we have shown that NTG-induced increases in cGMP levels wereattenuated dramatically in vascular smooth muscle. Thus, it seemedlikely that the IAS would also develop tolerance to the effects ofnitric oxide upon repeated or prolonged dosing.

In FIG. 6, 0.1% NTG in 5% dextrose/water with 1% propylene glycol wasadministered in bolus doses directly to the IAS via a Hamilton syringeattached to a Harvard automatic infusion pump at 20 μg/min every 30minutes. Each successive dose represented by asterisks produced adramatic drop in resting IASP followed by a complete recovery to restinglevels; a slight decline in resting pressures is observed over time, formost experiments, possibly due to the effects of anesthesia. Since eachNTG administration was able to provide similar level and duration ofpressure reduction, no nitrate related pressure tolerance was noted withrepeated NTG administration.

FIG. 7 demonstrates that a continuous infusion of NTG at 20 μg/hourproduced a steady and sustained decline in resting IASP with no evidenceof recovery in LASP during the entire treatment period, ruling out theincidence of tolerance, even after 4 hours of perfusion; asterisksindicate hours following initiation of NITG infusion. Similar resultswere obtained using a ten-fold higher dose of NTG. Since there was norebound of pressure reduction with continuous NTG administration, nonitrate related pressure tolerance was noted with continuous NTGadministration.

Surprisingly, we have found that tachyphylaxis to the relaxant effect ofNTG on the LAS does not develop with repeated or prolonged dosing invivo. Our in vitro studies have also found that NTG-induced increases incGMP levels in the muscle of the IAS which were not as attenuated asthose in vascular smooth muscle.

Example 6

This example illustrates the use of cyclic nucleotide analogs to affectIASP in the rat model.

8-bromo cAMP (0.1% in saline) was infused to the IAS at 20 μg/hour for 3hours. Minimal pressure reduction was noted; this could due to the poorabsorption of the 8-bromon cAMP from saline to the sphincter tissueduring the study duration (see FIG. 8).

Dibutyryl cAMP (0.1% in saline) was infused to the IAS at 20 μg/hour for3 hours. A minor depression in IASP was noted (see FIG. 9). cGMP analogsalso elicited very little depression of IASP, possibly due to the poorbioavailability through the in vivo topical dosage form.

Since increasing levels of cGMP and cAMP in the IAS with NTG or ISOresulted in an expected decrease in IASP, introduction of theaqueous-soluble 8-bromo and dibutyryl analogues of cGMP and cAMP werefully expected to also lower resting IASP in the rat model.Surprisingly, the cGMP analogs provided almost no effect on IASP (datanot shown), whereas dibutyryl cAMP proved to be more efficacious in therat model than the 8-bromo derivative as demonstrated in the followingfigures. These results may reflect differences in bioavailability of theanalogs and/or direct effects of the butyrate moiety on smooth musclerelaxation.

Example 7

This example illustrates the varying ability of superoxide scavengers topotentiate the effect of nitric oxide/nitric oxide donors in vivo.

The ability of superoxide scavenger superoxide dismutase (SOD) topotentiate the relaxing effects of NTG by prolonging the half-life ofnitric oxide (NO) was examined using the rat model. NO, produced fromthe enzymatic degradation of NTG within cells, has a half-life of only afew seconds before it is acted upon by oxygen radicals such as thesuperoxide anion to form peroxynitrite (Weller, 1997). Perfusion of theanal sphincter with SOD prior to NTG treatment, theoretically shouldremove superoxide from the equation, providing a longer half-life for NOin the tissue and resulting in more sustained cGMP levels, potentiatingthe NTG-induced relaxation of the IAS.

Vehicle (20 μl of 5% dextrose/water with 10% propylene glycol) wasdelivered to the IAS followed in 30 minutes by a 200 μg bolus deliveryof superoxide dismutase (SOD) in vehicle, followed 15 minutes later witha bolus dose of 200 μg NTG in the same vehicle. A significantpotentiation of NTG effect, e.g. increasing the duration of action onreducing anal sphincter was observed (see FIG. 10). This resultindicates that the activity of the NO donor in the presence of asuperoxide anion scavenger is enhanced.

Vehicle (20 μl of 5% dextrose/water with 10% propylene glycol) wasdelivered to the IAS followed in 30 minutes by a 200 μg bolus deliveryof NTG in vehicle, followed 15 minutes later with a bolus dose of 20 μgSOD. No significant potentiation of NTG was observed suggesting that thepotentiation effect of SOD is most pronounced when administered prior toNTG (see FIG. 11). This result suggests that the NTG-derived NO hasalready dissipated from the tissue.

Surprisingly, the synthetic superoxide scavenger Mn (III)tetrakis(4-benzoic acid) porphyrin chloride (MnTBAP), did notdemonstrate significant NO enhancing activity in this model.

Further, as FIGS. 10 and 11 demonstrate, SOD alone has little effect onIASP since the resting IAS has low endogenous levels of NO to act uponby superoxide anion.

Example 8

This example illustrates the potentiation of NTG in the rat model by PDEV inhibitor blockage of the cGMP-specific PDE activity.

Zaprinast:

The vehicle, 1-methyl 2-pyrollidinone (1M2P) was injectedintra-peritoneal (i.p.). (100 μl), 30 minutes prior to bolus doses ofNTG (20 μg/min every 30 minutes). The duration of depression of IASP dueto NTG was constant with each dose (see FIG. 12).

Zaprinast (10 mg in 100 μl 1M2P) was injected i.p. 30 minutes prior tobolus doses of NTG (20 μg/min every 30 minutes). There was an increasingduration of LASP depression with consecutive doses of NTG demonstratingpotentiation of NTG by a selective PDE V inhibitor (see FIG. 13).

The vehicle, 1-methyl 2-pyrollidinone (1M2P) was injectedintra-peritoneal (i.p.). (100 μl), followed after 2.75 hours by thefirst dose of NTG (20 μg/min every 30 minutes). The duration ofdepression of IASP was consistent with each NTG dose (see FIG. 14).

Zaprinast (10 mg in 100 μl 1M2P) was injected i.p. 2.75 hours prior tobolus doses of NTG (20 μg/min every 30 minutes). The duration ofdepression of IASP continued to increase with each NTG dose and peakedat around 3.5-4 hours and decreased with additional doses of NTG. Thisstudy suggests that an i.p. dose of zaprinast reaches maximal levels inthe IAS between 3.54 hours and causes potentiation with NTG (see FIG.15).

These results show that potentiation of NTG activity can be achieved byagents protecting from PDE degradation the cGMP formed through NOactivation of guanylyl cyclase.

Dipyridamole:

The vehicle, 1-methyl 2-pyrollidinone (1M2P) was injected i.p. (100 μl),50 minutes prior to bolus doses of NTG (20 μg/min every 30 minutes). Theduration of depression of IASP due to NTG was constant with each dose(see FIG. 16).

Dipyridamole (10 mg in 100 μl 1M2P) was injected i.p. 50 minutes priorto bolus doses of NTG (20 μg/min every 30 minutes). The duration ofdepression of IASP due to NTG was constant with each dose andapproximately twice that for the vehicle-treated rat (see FIG. 17).

MBCQ:

MBCQ (10 mg in 100 μl 1M2P) was injected i.p. 30 minutes prior to bolusdoses of NTG (20 μg/min every 30 minutes). No noticeable potentiation ofNTG was observed with this PDE V inhibitor in this experiment (see FIG.18). Bioavailability of MBCQ could be the cause of the minimal effectseen with this compound.

Whereas dipyridamole demonstrated less striking potentiation with NTG,the most potent of the PDE V inhibitors under in vitro conditions, MBCQ,did not demonstrate significant activity, potentially due to diminishedbioavailability of this drug in the in vivo model (data not shown).

Example 9

This example illustrates the effect of non-selective β-adrenergicagonists using isoproterenol. These agonists activate adenyl cyclase,thereby increasing cAMP levels, and act on the IASP through the directsmooth muscle relaxing activity of cAMP.

A bolus dose of 200 μg isoproterenol produced a dramatic drop in IASPeliminating significant pressure readings by the catheter/transducer infact, isoproterenol proved to be a very potent IAS relaxant and had tobe titred down, in another study, to a continuous dose of 0.2 μg/hour inorder to avoid significant drops in IASP (see FIG. 19).

Example 10

This example illustrates the effect of β₂-agonists on the IASP.

The β₂-agonist, terbutaline (in saline) was infused continuously at 20μg/hour. A steady and sustained decline in IASP over the 3 plus hours ofinfusion (FIG. 4 n, 20) resulted. The significant drop in IASPthroughout the experiment reached a plateau between 1.5 and 2 hours postinitiation of treatment.

This sustained, however moderate, drop in IASP is considered desirablefor prolonging the increased blood flow to the anoderm necessary forhealing anal fissures, without inducing a complete relaxation of the IASwhich might result in temporary incontinence.

The β₂-agonist, salbutamol (in saline) was infused continuously at 20μg/hour and demonstrated a significant drop in IASP throughout theexperiment similar to terbutaline (see FIG. 21).

Example 11

This example illustrates the effects of cAMP levels on the IASP and theeffects of PDE IV inhibitor blockage of the cAMP-specific PDE activityin the rat model.

Effects of Rolipram:

The PDE IV inhibitor rolipram, in 5% DMSO/Acetone:Olive oil 1:1 wascontinuously infused at 20 μg/hour rate. A pattern including significantdrops in IASP followed by shorter recovery phases occurred prior to 1hour after initiating the drug infusion (see FIG. 22).

Etazolate Potentiation of Salbutamol:

Delivery of 200 μg of salbutamol in saline to the IAS produced noshort-term effects on the IASP; however a subsequent treatment withsalbutamol plus the PDE IV inhibitor etazolate, also at 200 μg insaline, produced a dramatic and sustained drop in IASP, suggesting apotentiation effect of a β₂-agonist with a PDE IV inhibitor on analsphincter pressure reduction (see FIG. 23).

This experiment is similar to that described above for FIG. 23, howeverthe order of the delivery of the drugs was reversed. The results weresimilar (see FIG. 24).

Smooth muscle relaxation is caused by agents that elevate cAMP levelsvia phosphorylation of myosin light chain kinase by cAMP-dependentprotein kinase (PKA). PDE type IV inhibitors prevent degradation of cAMPby cAMP-specific PDE. As seen with the above PDE IV inhibitor etazolatepotentiation of the effects of the β₂-adrenergic agonist, salbutamol,potentiation of agents which activate adenylyl cyclase, can be achievedwith PDE type IV inhibitors.

Effects of RO-20-1724:

The PDE IV inhibitor RO-20-1724 was infused at 20 μg/hour in the vehicle5% DMSO/Acetone:Olive oil 1:1. The drop in IASP was minimal suggestingeither lack of bioavailability of the drug from the current route ofadministration (see FIG. 25).

Effects of Forskolin

The specific adenyl cyclase activator forskolin, was infused at 20μg/hour in the vehicle 5% DMSO/Acetone:Olive oil 1:1. A significant andsustained drop in IASP was observed (see FIGS. 26 (control) and 27).This experiment clearly demonstrates the contribution of cAMP ininducing relaxation of the internal anal sphincter.

Example 12

This example illustrates the use of α-adrenergic antagonists to reduceIASP in the rat model.

The α₁-blocker, prazosin in 5% DMSO/Acetone:Olive oil 1:1 was infused at20 μg/hour. A significant and sustained drop in IASP that plateauedafter 1 hour was observed suggesting that the increase of cAMP levelleads to relaxation of internal anal sphincter pressure (see FIG. 28).

Example 13

This example illustrates the effect of non-selective PDE Inhibitors onIASP in the rat model.

Isobutyl methylxanthine (IBMX) in 5% DMSO/Acetone:Olive oil 1:1 wasinfused at 200 μg/hour. A significant and sustained drop in IASP thatleveled off at 1 hour after initiation of the infusion was observed (seeFIG. 29).

Isobutyl methylxanthine (IBMX) in 5% DMSO/Acetone:Olive oil 1:1 wasinfused at a lower dose, i.e. 20 kg/hour. The results were similar asfor the experiment described in FIG. 29 (see FIG. 30).

The non-selective PDE inhibitor, IBMX is thought to act on smooth muscleby a number of potential mechanisms including: 1) PDE inhibition andincreasing cAMP levels; 2) effects on intracellular calciumconcentration; 3) effects on membrane hyperpolarization; 4) uncouplingof increased calcium levels with muscle contractility; and 5) adenosinereceptor antagonism (Goodman & Gilman's “The Pharmacological Basis ofTherapeutics” 9^(th) edition. Section IV-Autocoids; Drug Therapy ofInflammation).

Example 14

This example illustrates the use of K+-ATP Channel Openers to relax theIAS.

The K⁺-ATP channel openers, minoxidil and diazoxide, inducehyperpolarization of the cell membranes of smooth muscle, and therebyinactivate voltage-gated Ca²⁺ channels.

Minoxidil (830 μg in 20 μl 62.5% propylene glycol/water) was deliveredto the IAS. A significant and sustained drop in IASP was observedshortly after delivery of the drug (see FIG. 31).

Diazoxide in 5% DMSO/Acetone:Olive oil 1:1 was infused at 20—μg/hour. Adramatic drop in IASP was observed for the duration of the experiment(see FIG. 32).

Example 15

This example illustrates the use of Ca²⁺-channel blockers

Diltiazem in saline was infused at 20 μg/hour. The drug produced adramatic and sustained drop in IASP for the duration of the experiment(see FIG. 33).

Verapamil in saline was infused at 20 μg/hour. The drug produced adramatic and sustained drop in IASP for the duration of the experiment(see FIG. 34).

Example 16

This example illustrates the use of sympathetic nerve terminaldestroyers to achieve a long term reduction in IASP in the rat modelfollowing a short term administration of the active agent.

Neurogenic tone of the IAS is largely due to sympathetic adrenergicinnervation; norepinephrine released by the nerves acts on α₁-adrenergicreceptors to contract smooth muscle. Earlier reports suggested thatα-blockers reduced anal pressure in man (Speakman, C. T., Dig Dis Sci38(11):1961-9 (1993); Parks, A. G., Gut 10(8): 674-7 (1969)). Recentclinical trials using one of the most potent toxins known, botulinustoxin, produced by Clostridium botulinum, have demonstrated success inhealing anal fissures after multiple injections of the toxin directlyinto the IAS. Botulinus toxin presumably relaxes the IAS through itsaction of blocking acetylcholine (ACH) release from cholinergicpre-synaptic fibers (Kao, I., et al., Science 193, 1256-8 (1976)).However, cholinergic innervation of the IAS is not thought to contributesignificantly to LAS tone. We decided to use a drug that can be appliedtopically to the IAS, and that destroys adrenergic nerve terminals,thereby blocking the actions of norepinephrine in maintaining sphinctertone.

6-hydroxydopamine in saline was delivered to the IAS in bolus doses of200 μg to a rat each day for 5 days. The IASP was measured over threeweeks. A continuous drop in IASP was noted through day 16, 11 days aftertermination of the treatment. By day 19 a partial recovery in IASP wasobserved, and by day 22 the average IASP was 36% below the originalbaseline pressure (see FIG. 35).

Thus, treatment with 6-hydroxydopamine (6-OHDA), resulted in a prolongedreduction in IASP over at least a 3 week period following 5 dailytopical doses of 200 μg in saline to the rat IAS.

Example 17

This example illustrates the effects of a PDE III/IV inhibitor on IASPunder a variety of experimental conditions.

This experiment serves as a control for the experiment described in FIG.37. An i.p. injection of 100 μl 1M2P was followed in 30 minutes by acontinuous infusion of isoproterenol in saline at 0.2 μg/hour. Thissub-threshold dose of isoproterenol had no significant effect onlowering IASP (see FIG. 36).

The PDE III/V inhibitor, zardaverine (10 mg in 100 μl 1M2P) was injectedi.p. followed in 30 minutes by a continuous infusion of isoproterenol insaline at 0.2 μg/hour. A rapid drop in IASP was noted immediately afterthe i.p. injection of zardaverine, and a sustained decrease in averageIASP followed isoproterenol infusion. A continuous slow wave pattern ofdecreasing and increasing IASP was observed after isoproterenol infusion(see FIG. 37).

The PDE III/IV inhibitor, zardaverine (7.5 mg in 100 μl 1M2P) wasinjected i.p. followed in 30 minutes by a continuous infusion of 5%dextrose at 20 μl/hour. The zardaverine injection produced a rapid buttransient drop in IASP that soon returned to normal baseline levels. Thesubsequent infusion of 5% dextrose had no effect on lowering the IASP(see FIG. 38).

The PDE III/IV inhibitor, zardaverine (7.5 mg in 100 μl 1M2P) wasinjected i.p. followed in 30 minutes by a continuous infusion ofisoproterenol in saline at 0.2 μg/hour. Zardaverine, again induced arapid and transient decrease in IASP. The isoproterenol infusion furtherreduced the IASP to almost zero mmHg (see FIG. 39). These experiments(FIGS. 36-39) suggest a potentiation of subthreshold levels ofisoproterenol by zardaverine.

Example 18

This example illustrates the use of adenosine antagonists to relax theIAS in the rat model.

Theophylline:

Theophylline, an adenosine antagonist, was continuously infused at 200μg/hour in 5% dextrose. A dramatic and sustained drop in IASP wasobserved throughout the 4 hour duration of the experiment (see FIG. 40).

Theophylline was continuously infused at 20 μg/hour in 5% dextrose. Amoderate drop in average IASP was observed throughout the 3 hourduration of the experiment (see FIG. 41).

Theophylline was continuously infused at a lower dose, i.e. 2 μg/hour in5% dextrose. A minimal drop in average IASP was observed throughout the3 hour duration of the experiment (see FIG. 42).

Dyphylline:

FIG. 43 shows the IAS relaxing effects of a 20 μg/hr continuous dose ofdyphylline [7-(2,3-dihydroxypropyl) theophylline], a theophyllinederivative that is not metabolized by the liver and is excretedunchanged by the kidneys, providing this drug with a low toxicitypotential.

Example 19

This example illustrates a method for treating anal disorders in anindividual using phosphodiesterase inhibitors and other agents to reducepain associated with the disorders, including acute and chronic analfissures.

Patients with severe anal pain and especially during and after bowelmovement can be treated with the following therapies: zaprinast,zaprinast and nitroglycerin, minoxidil, nitroglycerin and cGMP mimetics,isoproterenol, or sildenafil, either one to three times daily or asrequired to effectively reduce anal rectal pain. Pain reduction(indicated by a reduction in the average pain and/or the defecationpain) will be evaluated and the time to pain reduction will also beevaluated. Therapy that is effective in relieving anal pain willeventually leads to effective resolution of these anal rectal disorders.Additionally, drugs that can effectively reduce anal sphincter pressure,maintain reduced anal sphincter pressure, or prevent recurrence of thediseases and yet cause minimal or no adverse reactions such as headache,dizziness, and hypotension will be of great therapeutic benefit.

Example 20

This example illustrates a method for treating anal disorders in anindividual using phosphodiesterase inhibitors and other agents topromote healing in acute and chronic anal fissures.

Patients with anal fissures can be treated with the following therapies:zaprinast, zaprinast and nitroglycerin, minoxidil, nitroglycerin andcGMP mimetics, isoproterenol, or sildenafil, either one to three timesdaily or as required to effectively promote healing. Healing isindicated by improving re-epithelization of the observed fissure and canbe evaluated along with the time needed to complete healing. Therapythat is effective in healing anal fissures eventually leads to completeresolution of these anal rectal disorders. Furthermore, drugs that caneffectively reduce anal sphincter pressure, maintain reduced analsphincter pressure, or prevent recurrence of the diseases and yet causeminimal or no adverse reactions such as headache will providesignificant medical benefit.

Example 21

This example illustrates a method to reduce bleeding in patients withhemorrhoidal symptoms or diseases.

Patients with hemorrhoidal symptoms or diseases can be treated with thefollowing therapies: zaprinast, zaprinast and nitroglycerin, minoxidil,nitroglycerin and cGMP mimetics, isoproterenol, or sildenafil, eitherone to three times daily or as required to effectively reduce bleedingand promote healing. Disease resolution indicated by reduction inbleeding and or pain can be evaluated along with the time to healing.Therapy that is effective in improving hemorrhoidal symptoms willeventually lead to complete resolution of these anal rectal disorders.Furthermore, drugs that can effectively reduce anal sphincter pressure,maintain reduced anal sphincter pressure, or prevent recurrence of thediseases while causing minimal or no adverse reactions such as headacheare of significant medical benefit.

Example 22

A composition of a base gel comprising 1.0 gm of salbutamol, 0.6 gm ofcarbopol 1342 USP, 35.44 gm of propylene glycol, 15.16 gm of dehydratedethanol USP, 15.16 gm of isopropyl alcohol USP, 2.5% oleic acid,triethanolamine HCl 1N to adjust the pH from 6.0 to 7.0, 0.05 gm ofbutylated hydroxytoluene NF, and 29.72 gm of purified water USP. Otherconcentrations of salbutamol can be added in the same gel base toachieve the therapeutically effective dose; this can also be achieved byadjusting the concentration of other, β-agonists with gel baseexcipients such as oleic acid.

Example 23

One example of a topical composition comprises 0.05 to 1% sildenafil,75% (w/w) white petrolatum USP, 4% (w/w) paraffin wax USP/NF, lanolin14% (w/w), 2% sorbitan sesquioleate NF, and 4% propylene glycol USP atthe therapeutic effective dose to the anorectal area. Typically, the 50mg to 600 mg of sildenafil ointment can be applied to the anorectal areain order to reduce the signs and/or symptoms associated with anorectaldisorders, for example, anal fissure, anal ulcers, and hemorrhoidaldiseases. The concentration of sildenafil, or other phosphodiesteraseinhibitors can be varied by adjusting the ratio between the sildenafilwith excipients facilitate either the attachment of sildenafil to thelocal tissue, or agents enhance absorption to the afflicted tissue.

Yet another example of a topical composition comprises nitroglycerin at0.1% concentration and sildenafil at 0.1% concentration can beincorporated in the same ointment base as mentioned above. Thiscomposition can be applied topically from a metered dosing device wherea 50 mg to 1.5 gm dose of the composition is administered to theafflicted anorectal tissue to achieve the desired therapeutic effects.

Another therapeutic regimen is to provide patients afflicted with theanorectal disorders with both oral sildenafil tablets and topicalnitroglycerin ointment. These two dosage forms can be used incombinations which provide the best efficacy and compliance among thesepatients.

Example 24

A composition of aminothylline topical spray composition comprises 0.1to 5.0% (w/w) of aminothylline, acetylated lanolin alcohol, aloe vera,butane, cetyl acetate, hydrofluorocarbon, methyl paraben, PEG-8 laurateand polysorbate 80 in a 2 oz. pump spray bottle. The concentration ofaminophylline or other non-specific phosphodiesterase inhibitor can varybetween 0.5% to 5%. Other non-hydrofluorocarbon propellant can also beused instead of hydrofluorocarbon in the current composition. Thiscomposition can be sprayed directly onto the afflicted tissue once tofour times daily to achieve the desired relief of signs and/or symptomsassociated with anorectal disorders. This composition can also includementhol and benzocaine to provide the immediate local pain relief andsoothing sensation whereas aminophylline provides the longer lastingrelaxation of anal sphincter pressure.

Example 25

A base cream composition comprises 2 gm prazosin hydrochloride (2.0%w/w), 54.3 gm of purified water USP, 2 gm of Sepigel 305, 4.5 gm ofCrodamol, 5.0 gm of glycerin, 6.0 gm sesame oil, 15.0 gm of whitepetrolatum USP, 2.0 gm of lanolin USP, 7.0 gm of 1,3-butylene glycol,0.2 gm of methylparaben and 2.0 gm of silicon HL88.

A base cream can be prepared by first separate mixings of aqueous versusnon-aqueous, i.e. oil phase, components of the cream. Once the aqueousphase containing the prazosin hydrochloride is well mixed, the meltedoil phase is gently stirred into the aqueous phase to form a uniformcream base.

Example 26

Sildenafil, a specific inhibitor of type V phosphodiesterase, can begiven orally via a tablet parenterally or can be applied topically topatients diagnosed with anal fissures, either acute or chronic analfissures, or other anorectal disorders. Sildenafil can be given one tothree times daily for 8 weeks, especially in the case of patientsafflicted with chronic anal fissure to cause the reduction of signs andsymptoms associated with anorectal disorders.

For topical application, an approximate 50 mg to 900 mg dose of thecream measured by a metered dosing device, containing sildenafil, at theconcentration from 0.02% to 5%, can be applied to the afflictedanorectal region using an applicator or by finger, one to four timesdaily to achieve the desirable therapeutic effects. Alternatively, theoral and topical treatment can be used in a defined regimen to achievethe best therapeutic effects.

Example 27

A phosphodiesterase inhibitor, for example aminophylline, can be giveneither orally via a tablet, parenterally or can be applied to patientsdiagnosed with anal fissures or other anorectal disorders, either acuteor chronic anal fissures from a topical dosage form, e.g. a cream. Fortopical application, an approximate 50 mg to 900 mg of the creammeasured by a metered dose device, can be applied to the afflictedanorectal region using an applicator or by finger, one to four timesdaily to achieve the desirable therapeutic effects.

Example 28

A β-adrenergic agonist, for example salbutamol, can be given from asuppository dosage form to patients diagnosed with anal fissures orother anorectal disorders, either acute or chronic anal fissures from atopical dosage form, e.g. a cream. For suppository application, anapproximate 300 mg to 3 gm of the suppository unit can be applied to theafflicted anorectal region using an applicator or by finger, one to fourtimes daily. Once the suppository melts in the anal cavity, thesalbutamol released from the dosage form is available to achieve thedesirable therapeutic effects.

Example 29

An α-adrenergic-antagonist, i.e. prazosin can be applied from a topicalspray to patients diagnosed with hemorrhoidal disorders, alone or incombination with a local anesthetic, for example, lidocaine, or incombination with a mixed β₂- and β₃-adrenergic agonist, for examplesalbutamol, or in combination with a PDE IV inhibitor, for example,ariflo (SB207499), RP73401, CDP840, rolipram and LAS31025. Prazosin canbe applied directly to the afflicted area with the propellant from thespray and can be used as needed to relieve the local pain and analsphincter hypertonicity. Eventually, the application of prazosin leadsto healing of the hemorrhoidal disorders.

Example 30

This example illustrates the preparation of a theophylline topicalformulation from theophylline oral tablets.

Five Theo-24 tablets (400 mg of theophylline per tablet; UCBPharmaceuticals, Inc.) were combined and ground into a fine powder. Tothis powder, 50 ml of ethanol was added and the solution was stirred atroom temperature for 15 minutes. Next, 48 ml of propylene glycol and 100ml of distilled water were added to the ethanol mixture while stirring.This mixture was stirred for 15 minutes, at which time the powder wascompletely dissolved. A solution of carbopol in distilled water was thenadded to the mixture while stirring, forming a 1% topical theophyllinegel. The resulting gel was then stirred for another 15 minutes.

Example 31

A methylxanthine derivative, for example diphylline or theophylline, canbe given either orally via a tablet, parenterally or can be applied topatients diagnosed with anal fissures or other anorectal disorders,either acute or chronic anal fissures from a topical dosage form, e.g. acream or a rectal suppository.

For topical application, an approximate 50 mg to 900 mg of the creammeasured by a metered dose device, can be applied to the afflictedanorectal region using an applicator or by finger, one to four timesdaily to achieve the desirable therapeutic effects.

It is understood that the examples and embodiments described herein arefor illustrative purposes only and that various modifications or changesin light thereof will be suggested to persons skilled in the art and areto be included within the spirit and purview of this application andscope of the appended claims. All publications, patents, and patentapplications cited herein are hereby incorporated by reference in theirentirety for all purposes.

1. A method of treating an anorectal disorder, and for controlling thepain associated therewith, the method comprising administering to asubject in need of such treatment a therapeutically effective amount ofa composition that comprises at least one internal anal sphincterrelaxing agent selected from the group consisting of NO donors,phosphodiesterase type II inhibitors, phosphodiesterase type IVinhibitors, phosphodiesterase type V inhibitors, nonspecificphosphodiesterase inhibitors, superoxide scavengers, β-adrenergicagonists, cAMP-dependent protein kinase activators, α₁-adrenergicantagonists, estrogens, L-type Ca²⁺ channel blockers, ATP-sensitive K⁺channel activators, adenosine receptor antagonists and smooth musclerelaxants.
 2. A method in accordance with claim 1, wherein saidadministering is by local application.
 3. A method according to claim 1,wherein said composition comprises a first relaxing agent that is a NOdonor selected from the group consisting of nitroglycerin, L-arginine,SNAP, GSNO and SIN-1 and a second agent is selected from the groupconsisting of β₂-adrenergic agonists and adrenergic receptorantagonists.
 4. A method in accordance with claim 1, wherein saidcomposition comprises a first relaxing agent which is a NO donorselected from the group consisting of nitroglycerin, L-arginine, SNAP,GSNO and SIN-1 and a second agent which is an ATP sensitive K⁺ channelactivator, an adenosine receptor antagonist, or a β₂-adrenergic agonist.5. A method according to claim 1, wherein said composition comprises anadenosine receptor antagonist, an ATP sensitive K⁺ channel opener, or aβ₂-adrenergic agonist.
 6. A method in accordance with claim 1, whereinsaid anorectal disorder is an anal fissure.
 7. A method of claim 1,wherein said composition comprises a terbutaline, salbutamol,theophylline, dyphylline, minoxidil or diazoxide.
 8. A method oftreating an anorectal disorder in a human, and for controlling the painassociated therewith, said method consisting essentially ofadministering a first agent which consists essentially of a selectivePDE V inhibitor to said human.
 9. A method according to claim 8, whereinsaid method consists essentially of administering sildenafil as said PDEV inhibitor.
 10. A method according to claim 8, wherein said inhibitoris zaprinist, DMPPO, or MY-5445.
 11. A method according to claim 8,wherein said administering is via the oral route.
 12. A method accordingto claim 11, wherein said inhibitor is in the form of a lozenge, tabletor capsule.
 13. A method according to claim 8, wherein said disorder isselected from the group consisting of anal fissure, anal ulcer,hemorrhoidal diseases, levator spasm, disorders associated withhemorrhoidal pain, spasm of the internal anal sphincter, andpost-operative rectal pain.
 14. A method according to claim 13, whereinsaid disorder is anal fissure.
 15. A method according to claim 13,wherein said disorder is a hemorrhoidal disease.
 16. A method accordingto claim 13, wherein said disorder is post-operative rectal pain.
 17. Amethod according to claim 13, wherein the disorder is exacerbated byhypertonicity or spasms of the anal sphincter muscle.
 18. A methodaccording to claim 9, wherein said administering is via the oral route.19. A method according to claim 9, wherein said sildenafil isadministered as a lozenge, tablet or capsule.
 20. A method according toclaim 9, wherein said disorder is anal fissure.
 21. A method accordingto claim 8, wherein said administering is via the rectal route.